Science 9-Q2 PIVOT 4A Module (1) PDF

QUARTER 2 Science G9  Republic Act 8293, section 176 states that: No copyright shall subsist in any work of the Government of the Philippines. However, prior approval of the government agency or office wherein the work is created shall be necessary for exploitation of such work for profit. S...

QUARTER 2 Science G9  Republic Act 8293, section 176 states that: No copyright shall subsist in any work of the Government of the Philippines. However, prior approval of the government agency or office wherein the work is created shall be necessary for exploitation of such work for profit. Such agency or office may, among other things, impose as a condition the payment of royalties. Borrowed materials (songs, stories, poems, pictures, photos, brand names, trademarks, etc.) included in this book are owned by their respective copyright holders. Every effort has been exerted to locate and seek permission to use these materials from their respective copyright owners. The publisher and the authors do not represent nor claim ownership over them. This module was carefully examined and revised in accordance with the standards prescribed by the DepEd Regional Office 4A and CLMD CALABARZON. All parts and sections of the module are assured not to have violated any rules stated in the Intellectual Property Rights for learning standards. The Editors PIVOT 4A Learner’s Material Quarter 2 First Edition, 2020 Science Grade 9 Job S. Zape, Jr. PIVOT 4A Instructional Design & Development Lead Owen Agustin Peña Content Creator & Writer Jhonathan S. Cadavido Internal Reviewer & Editor Lhovie A. Cauilan & Jael Faith T. Ledesma Layout Artist & Illustrator Jhucel A. del Rosario & Melanie Mae N. Moreno Graphic Artist & Cover Designer Ephraim L. Gibas IT & Logistics Crist John Pastor, Philippine Normal University External Reviewer & Language Editor Published by: Department of Education Region IV-A CALABARZON Regional Director: Wilfredo E. Cabral Assistant Regional Director: Ruth L. Fuentes  Guide in Using PIVOT 4A Learner’s Material For the Parents/Guardians This module aims to assist you, dear parents, guardians, or siblings of the learners, to understand how materials and activities are used in the new normal. It is designed to provide information, activities, and new learning that learners need to work on. Activities presented in this module are based on the Most Essential Learning Competencies (MELCs) in Science as prescribed by the Department of Education. Further, this learning resource hopes to engage the learners in guided and independent learning activities at their own pace. Furthermore, this also aims to help learners acquire the essential 21st century skills while taking into consideration their needs and circumstances. You are expected to assist the children in the tasks and ensure the learner’s mastery of the subject matter. Be reminded that learners have to answer all the activities in their own answer sheet. For the Learners The module is designed to suit your needs and interests using the IDEA instructional process. This will help you attain the prescribed grade-level knowledge, skills, attitude, and values at your own pace outside the normal classroom setting. The module is composed of different types of activities that are arranged according to graduated levels of difficulty—from simple to complex. You are expected to : a. answer all activities on separate sheets of paper; b. accomplish the PIVOT Assessment Card for Learners on page 38 by providing the appropriate symbols that correspond to your personal assessment of your performance; and c. submit the outputs to your respective teachers on the time and date agreed upon.  Parts of PIVOT 4A Learner’s Material K to 12 Learning Descriptions Delivery Process Introduction This part presents the MELC/s and the desired What I need to know learning outcomes for the day or week, purpose of the lesson, core content and relevant samples. This maximizes awareness of his/her own What is new knowledge as regards content and skills required for the lesson. This part presents activities, tasks and contents What I know of value and interest to learner. This exposes Development him/her on what he/she knew, what he/she does What is in not know and what he/she wants to know and learn. Most of the activities and tasks simply and directly revolve around the concepts of What is it developing mastery of the target skills or MELC/s. In this part, the learner engages in various tasks What is more and opportunities in building his/her knowledge, skills and attitude/values (KSAVs) to meaningfully connect his/her concepts after Engagement doing the tasks in the D part. This also exposes What I can do him/her to real life situations/tasks that shall: ignite his/ her interests to meet the expectation; make his/her performance satisfactory; and/or produce a product or performance which will help What else I can do him/her fully understand the target skills and concepts. This part brings the learner to a process where he/she shall demonstrate ideas, interpretation, What I have learned mindset or values and create pieces of Assimilation information that will form part of his/her knowledge in reflecting, relating or using them effectively in any situation or context. Also, this What I can achieve part encourages him/her in creating conceptual structures giving him/her the avenue to integrate new and old learnings. This module is a guide and a resource of information in understanding the Most Essential Learning Competencies (MELCs). Understanding the target contents and skills can be further enriched thru the K to 12 Learning Materials and other supplementary materials such as Worktexts and Textbooks provided by schools and/or Schools Division Offices, and thru other learning delivery modalities, including radio-based instruction (RBI) and TV-based instruction (TVI). WEEK The Quantum Mechanical Model 1 I Lesson At the beginning of the 20th century, a new field of study known as quantum mechanics emerged. One of the founders of this field was a Danish physicist Niels Bohr, who was interested in explaining the discrete line spectrum observed when light was emitted by different elements. Bohr was also interested in the structure of the atom, which was a topic of much debate at the time. Numerous models of the atom had been postulated based on experimental results including the discovery of the electron by J. J. Thomson and the discovery of the nucleus by Ernest Rutherford. Bohr supported the planetary model, in which electrons revolved around a positively charged nucleus like the rings around Saturn—or alternatively, the planets around the sun. Fig. 1 Solar System Model; planets revolving around the sun In this lesson, you will learn how the Quantum Mechanical Model of the atom describes the energies and positions of the electrons. In particular, we will develop a picture of the electron arrangements in atoms – a picture that allows us to account for the chemistry of the various elements. Let’s start by reviewing the Bohr’s model of the atom. The Bohr Model of the Atom In 1911, at the age of twenty-five, Niels Bohr received his Ph.D. in Physics. He was convinced that the atom could be pictured as a small positive nucleus with electrons orbiting around it. Over the next two years, Bohr constructed a model of the hydrogen atom with quantized energy levels. Bohr pictured the electron moving in circular orbits corresponding to the various allowed energy levels. He suggested that the electron could jump to a different orbit by absorbing or emitting a photon of light with exactly the correct energy content. PIVOT 4A CALABARZON Science G9 6  At first, Bohr’s model appeared very promising. It fit the hydrogen atom very well. However, when this model was applied to atoms other than hydrogen, it did not work. In fact, further experiments showed that the Bohr’s model is fundamentally incorrect. Although the Bohr model paved the way for later theories, it is important to realize that the current theory of atomic structure is not the same as the Bohr model. Electrons do not move around the nucleus in circular orbits like planets orbiting the sun. Surprisingly, as we shall see later in this lesson, we do not know exactly how the electrons move in an atom. The Wave Mechanical Model of the Atom By the mid-1920s, it had become apparent that the Bohr’s model was incorrect. Scientists needed to pursue a totally new approach. Two young physicists, Louis Victor De Broglie from France and Erwin Schrödinger from Austria, suggested that because light seems to have both wave and particle characteristics (it behaves simultaneously as a wave and as a stream of particle), the electron might also exhibit both of these characteristics. Although everyone had assumed that the electron was a tiny particle, these scientists said it might be useful to find out whether it could be described as a wave. When Schrödinger carried out a mathematical analysis based on this idea, he found out that it led to a new model for the hydrogen atom that seemed to apply equally well to other atoms – something Bohr’s model failed to do. We will now explore a general picture of this model, which is called the wave mechanical model of the atom. In the Bohr’s model, the electron was assumed to move in circular orbits. In the wave mechanical model, on the other hand, introduced a mathematical description of the electron’s motion called a wave function or atomic orbital. Orbitals are nothing like orbits. Squaring the orbital gives the volume of space in which the probability of finding the electron is high, the electron cloud (electron density). The model in Figure 3, gives no information about when the electron occupies a certain point in space or how it moves. In fact, we have good reasons to believe that we can never know the details of electron motion. But one thing we feel confident about is that the electron does not orbit the nucleus in circles as Bohr suggested. Schrödinger’s equation required the use of quantum numbers to describe each electron within an atom corresponding to the orbital size, shape, and orientation in space. Later it was found that one needed a quantum number associated with the electron spin. Quantum Numbers and Orbitals The first quantum number is the principle quantum number (n) that describes the size and energy of the or- bital and relative distance from the nucleus. The possible values of n are positive integers (1, 2, 3, 4 and so on). The smaller the value of n, the lower the energy, and the closer to the orbital is to the nucleus. We sometimes refer to the principle quantum number as designating the shell the electron is occupying. 7 PIVOT 4A CALABARZON Science G9  Each shell contains one or more subshells, each with one or more orbitals. The second quantum number is the angular momentum quantum number (l) that describe the shape of the orbitals. Its value is related to the principle quantum number and has allowed value of 0 to (n-1). For example, if n = 4, then the possible values of l would be 0, 1, 2, and 3 (= 4-1). Things to remember:  If l = 0, then the orbital is called an s-orbital and has a spherical shape with the nucleus at the center of the sphere. The greater the value of n, the larger is the sphere.  If l = 1, then the orbital is called a p-orbital with two lobes of high electron density on either side of the nucleus, for an hourglass or dumbbell shape.  If l = 2, then the orbital is a d-orbital with a variety of shapes.  If l = 3, then the orbital is an f-orbital with more complex shapes Fig. 4 An s-orbital (sharp) has spherical shape; a p-orbital (principal) has two lobes; a d-orbital (diffuse) has four lobes; and an f-orbital (fundamental) has eight lobes. The third quantum number is the magnetic quantum number (ml). It describes the orientation of the orbital sound around the nucleus. The possible values of m l depend upon the value of the l quantum number. The allowed values for m l are -l though 0 to +l. For example, for l = 3, the possible values of m l would be -3, -2, -1, 0, +1, +2, +3. This is why, for example if l = 1 (a p-orbital), there are three p-orbitals (sublevels) corresponding to ml values of -1, 0, +1. The fourth quantum number is the spin quantum number (ms) and indicates the direction the electron is spinning. There are only two possible values for m s: +1/2 and -1/2. When two electrons are to occupy the same orbital, then one must have an ms = +1/2 and the other electron must have an ms = -1/2. These are spin paired electrons. ASSIGNING THE FOUR QUANTUM NUMBERS To assign the four quantum numbers for an electron, let’s have an example: Question 1: If n = 7, what are the possible values of l ? Answer: Since l can be zero or a positive integer less than (n-1), it can have a value of 0, 1, 2, 3, 4, 5, 6. PIVOT 4A CALABARZON Science G9 8  Question 2: If n = 3 and l = 2, then what are the possible values of ml? Answer: Since ml must range from -l to +l , then ml can be: -2, -1, 0, 1, 2. Question 3: List all the possible combinations of all four quantum numbers when n = 2, l = 1, and ml = 0. Answer: The fourth quantum number is independent of the first three, allowing the allowing the first three quantum numbers of two electrons to be the same. Since the spin can be +1/2 or =1/2, there are two combinations: n = 2, l = 1, ml = 0, ms = +1/2 and n = 2, l = 1, ml = 0 ms = -1/2 Electron Configuration Quantum Mechanics may be used to determine the arrangement of the electrons within an atom if two specific principles are applied: the Pauli exclusion principle and the aufbau principle. The Pauli exclusion principle states that no two electrons in an atom can have the same set of the four quantum numbers. For example, if an electron has the following set of quantum numbers: n = 1, l = 0, ml = 0 ms = +1/2, then no other electron in that atom may have the same set. The Pauli exclusion principle limits all orbitals to only two electrons. The second principle, the aufbau principle, describes the order in which the electrons enter the different orbitals and sublevels. The arrangement of electrons builds up from the lowest energy level. The most stable arrangement of electrons has all the electrons with the lowest possible energy. This lowest energy arrangement is the ground state. Less stable (higher energy) arrangements are the excited states. An atom may have any number of excited arrangements, but there is only one ground state. There are several ways to of indicating the arrangement of the electrons in an atom. The most common way is the electron configuration. The electron configuration the use of the n and l quantum numbers along with the number of electrons. The principle quantum number, n, is represented by an integer (1, 2, 3…), and a letter represents the l quantum number (0 = s, 1 = p, 2 = d, and 3 = f). Any s-subshell can hold a maximum of 2 electrons, any p-subshell can hold up to 6 electrons, any d-subshell can hold a maximum of 10 electrons, and f-subshell can hold up to 14 electrons. The electron configuration for fluorine (nine electrons) is: 1s22s22p5 The figure below shows the one way of remembering the pattern for filling the atomic orbitals. The filling begins at the top of the pattern and follows the first arrow. When you reach at the end of the first arrow, you go to the second arrow and follow it to the end. The third arrow continues the pattern. 9 PIVOT 4A CALABARZON Science G9  Fig. 5 Filling Atomic Orbitals We can also represent the electron configuration by using a box diagram, in which orbitals are represented by boxes grouped by sublevel with small arrows indicating the electrons. The s-orbital is represented as 1 box with maximum of 2 electrons; p-orbital having 3 boxes with maximum of 6 electrons; d-orbital having 5 boxes with maximum of 10 electrons; and f-orbital having 7 boxes with maximum of 14 electrons. and so forth: 1s 2p 3d10 4f14 In applying electrons to the boxes using the arrows, you must first complete the “upward arrows” for all boxes before applying the remaining “downward arrows”. Let’s have an example: For hydrogen, the electron configuration and box diagram are H: 1s1 Configuration Box Diagram The arrow represents an electron spinning in a particular direction. The next element is helium, it has two protons in its nucleus and so has two electrons. Because the 1s orbital is the most desirable, both electrons go there but with opposite spins. For helium, the electron configuration and box diagram are He: 1s2 For fluorine, the electron configurations and box diagram (nine electrons) are 1s 2s 2p Fe: 1s22s22p5 PIVOT 4A CALABARZON Science G9 10  D Learning Task 1: Write TRUE if the statement is correct and write FALSE if the statement is incorrect. Write your answer on a separate sheet of paper. 1. The smaller the value of n, the lower the energy, and the closer to the orbital is to the nucleus. 2. If l = 1, then the orbital is called a d-orbital; looks like an hourglass or dumbbell shape. 3. If n = 5, the possible values of l are 0, 1, 2, 3, 4, 5. 4. The Pauli exclusion principle states that no two electrons in an atom can have the same set of the four quantum numbers. 5. Using box diagram, d-orbital can be represented by having 5 electrons with maximum of 10 boxes. E Learning Task 3: Answer the following questions. Write your answer in a separate sheet. 1. List all the four quantum numbers. a. b. c. d. 2. If n = 6, What are the values of l ? 3. If n = 7 and l = 5, then what are the possible values of ml? 4. If the values of l are 0, 1, 2, 3, 4, 5, 6, 7, 8 what is the value of n? A Learning Task 5: Choose the letter of the correct answer. Write your answer on a separate sheet of paper. 1. What is the electronic configuration of Lithium? (Lithium has 3 electrons) A. 1s12s2 B. 1s3 C. 1s12s12p1 D. 1s22s1 2. Boron has 5 electrons. Which of the following below is Boron’s electronic configuration? A. 1s5 B. 1s22s22p1 C. 1s22s12p2 D. 1s12s22p2 3. Any s-subshell can hold up to maximum of how many electrons? A. 10 B. 14 C. 2 D. 6 4. Any d-subshell can hold up to maximum of how many electrons? A. 10 B. 14 C. 2 D. 6 5. The second quantum number is the ___________ that describe the shape of the orbitals. A. Principal quantum number C. Magnetic quantum number B. Angular momentum quantum number D. Spin quantum number 11 PIVOT 4A CALABARZON Science G9 WEEK Chemical Bonding 2 Lesson I The world around us is composed almost entirely of compounds and mixtures of compounds. Rocks, coal, soil, petroleum, trees, and even us, human beings are all complex mixtures of chemical compounds in which different kinds of atom are bound together. The manner in which atom are bound together has a profound effect on the chemical and physical properties of substances. For example, both graphite and diamond are composed solely of carbon atoms. However, graphite is a soft, slippery material used in pencils, and diamond is one of the hardest materials known, valuable both as a gemstone and in industrial cutting tools. The question is, why do these materials, both composed of solely of carbon atoms, have such different properties? The answer lies in different ways in which the carbon atoms are bound to each other in these substances. Fig. 1 Diamond, composed of carbon atoms bonded together to produce one of the hardest materials known, makes a beautiful gemstone. Molecular bonding and structure play the central role in determining the course of chemical reactions, many of which are vital to our survival. To understand the behavior of natural materials, we must understand the nature of chemical bonding and the factors that control the structures of compounds. In this lesson, we will present various classes of compounds that illustrate the different types of bonds. We will then develop models to describe the structure and bonding that characterize the materials found in nature with its respective properties. Types of Chemical Bonding What is a chemical bond? Although there are several possible ways to answer this question, we will define a bond as a force that holds groups of two or more atoms together and makes them function as a unit. For example, in water, the fundamental unit is the H – O – H molecule, which we describe as being held together by the two O – H bonds. We can obtain information about the strength of a bond by measuring the energy required to break the Fig. 2 A water molecule. Solid sodium chloride is dissolved in water, the resulting solution conducts electricity, a fact that convinces chemists that sodium chloride is composed of Na- and Cl- ions. Thus, when sodium and chlorine react to form sodium chloride, electrons are transferred from the sodium atoms to the chlorine atoms to form Na- and Cl- ions, which then aggregate to form solid sodium chloride. The resulting solid sodium chloride is a very sturdy material; it has a melting point of approximately 800˚C. The strong bonding forces present in sodium chloride result from the attractions among the closely packed, oppositely charged ions. This is an example of ionic bonding. Ionic substances are formed when an atom that loses electrons relatively easily reacts with an atom that has a high affinity for electrons. In other words, an ionic compound results when a metal reacts with a nonmetal. PIVOT 4A CALABARZON Science G9 12  Metal Nonmetal Ionic Compound Table 1: SOME COMMON IONIC COMPOUNDS AND THEIR USES Name and Formula Uses Sodium Chloride (NaCl) Food preparation; manufacture of chlorine and sodium hydroxide Cobalt Chloride (CoCl2) Known as silica gel which absorbs water Potassium Iodide (KI) Iodine supplement in iodized salt Silver Nitrate (AgNO3) Antiseptic and Germicide Sodium Nitrite (NaNO2) Meat Preservation additive Aluminum Chloride (AlCl3) Used in deodorants Potassium Nitrate (KNO3) Used in gunpowder, matches, and fireworks. We have seen that a bonding force develops when two very different types of atoms react to form oppositely charged ions. But how does a bonding force develop between two identical atoms? Let us explore this situation by considering what happens when two hydrogen atoms are brought close together, as shown in Figure 3a. When hydrogen atoms are close together, the two electrons are simultaneously attracted to both nuclei. Note in Figure 3b how the electron probability increases between the two nuclei indicating that the electrons are shared by the two nuclei. (a) (b) Fig. 3 The formation of a bond between two hydrogen atoms, (a) Two separate hydrogen atoms. (b) When two hydrogen atoms come close together, the two electrons are attracted simultaneously by both nuclei. This produces the bond.a Note the relatively large electron probability between the nuclei indicating sharing of the electrons. The type of bonding we encounter in the hydrogen molecule and in many other molecules where electrons are shared by nuclei is called covalent bonding. Note that in the H2 molecule, the electrons reside primarily in the space between the two nuclei, where they are attracted simultaneously by both protons. When we say that a bond is formed between the hydrogen atoms, we mean that the H 2 molecule is more stable than two separated hydrogen atoms by a certain quantity of bond energy. A bond like this is called nonpolar covalent bond, or simply a covalent bond. In cases where the 13 PIVOT 4A CALABARZON Science G9  two atoms involved in the covalent bond are not the same, then the attraction is not equal. The bonding electrons are pulled more toward the atom with the greater attraction (more electronegative atom). This bond is a polar covalent bond. The atom that has the greater attraction takes on a partial negative charge and the other atom a partial positive charge. Some of the common examples of covalent bonding are: 1. Water. It consists of a covalent bond containing hydrogen and oxygen bonding together to make H2O. In this atomic molecule, two hydrogen atoms share their single electrons with the oxygen atom, which shares its own two electrons in return. 2. Diamond. A diamond is an example of giant covalent bond of carbon. A diamond has a giant molecular structure. Each carbon atom is covalently bonded to four other carbon atoms. Electrons are borrowed from these other carbon atoms. There is a tremendous amount of energy needed to separate the atoms in a diamond. This is because a covalent bond is strong and a diamond contains four covalent bonds. This makes the melting and boiling point if the diamond very high. 3. Rubber. Rubber is sticky when warm and brittle when cold. In 1939, Charles Goodyear accidently dropped a mixture of sulfur and natural rubber on a hot stove. The mixture heated up and became tough and elastic, forming vulcanized rubber. What happened? The covalent bonds transformed sulfur and natural rubber into the vulcanized rubber when it was heated. It changed because the covalent bonds between sulfur and rubber changed. We see in the previous section that when a metal and a nonmetal react, one or more electrons are transferred from the metal to the nonmetal to give ionic bonding. On the other hand, two identical atoms react to form a covalent bond in which electrons are shared equally. We can also distinguish a bond based on its properties. But, how do you know if a compound is ionic or covalent just by looking at a sample? This is where the properties of ionic and covalent compounds can be useful. Because there are exceptions, you need to look at several properties to determine whether a sample is ionic or covalent, but here are some characteristics to consider: Table 2: COMPARISON CHART OF PROPERTIES BASIS FOR COMPARISON IONIC BOND COVALENT BOND Existence Exist in the solid state Exist as solids, liquids and only. gasses. Occurs between Non-metal and metal. Between two non-metals. Conductivity - is the measure of Low conductivity. Very low conductivity. the ease at which an electric charge or heat can pass through a material. Hardness - is the resistance of a These are hard, These are not very hard, material to deformation of an in- because of the though exceptions are sili- denter of specific size and shape crystalline nature. con, diamond and under a known load carbon. PIVOT 4A CALABARZON Science G9 14  Melting and Boiling Points – The boiling High. Low. point is the temperature at which a material changes from a liquid to a gas (boils) while the melting point is the temperature at which a material changes from a solid to a liquid (melts). Keep in mind that a material's melting point is the same as its freezing point. Malleability - These are These are the state of being shaped, as by non-malleable. non-malleable. hammering or pressing into thin sheets Ductility - the capacity to undergo a change Non-ductile. Non-ductile. of physical form without breaking Volatility - tendency of a substance to evapo- Low. High. rate at normal temperatures. Solubility - is a property referring to the abil- Usually insoluble in Usually soluble in water ity for a given substance, the solute, to dis- water but soluble in but insoluble in organic solve in a solvent organic solvents such solvents such as ether, as ether, alcohol, alcohol, benzene, benzene, tetrachloromethane, tetrachloromethane, propanone and other propanone and other The next table shows the melting and boiling points of some ionic compounds: Table 3: Ionic Bonding Melting and Boiling Points Ionic Compound Melting point (°C) Boiling point (°C) Calcium Oxide, CaO 2580 2850 Magnesium Chloride, MgCl2 714 1412 Sodium Fluoride, NaF 993 1695 Aluminum Oxide, Al2O3 2030 2970 Sodium Chloride, NaCl 801 1420 A lot of heat energy is needed to break the strong ionic bonds during melting or boiling. Hence, ionic compounds have high melting and boiling points with low volatility. Table 4: Covalent Bonding Melting and Boiling Points Covalent compound Melting point (°C) Boiling point (°C) Ethanol, C2H5OH -117 78 Tetrachloromethane, CCl4 -23 76.8 Ammonia, NH3 -78 -33 Methane, CH4 -182 -164 A small amount of heat energy is required to overcome the weak intermolecular forces of attraction during melting or boiling. Hence, the covalent compound has low melting and boiling points with high volatility. 15 PIVOT 4A CALABARZON Science G9  D Learning Task 1: Match the definition in column A with the correct terms in column B. Write your answers in a separate sheet of paper. A B 1. The capacity to undergo a change of physical form without A. Accuracy breaking B. Conductivity 2. The resistance of a material to deformation of an indenter C. Ductility of specific size and shape under a known load D. Solubility 3. Occurs between metals and nonmetals E. Boiling Point 4. The measure of the ease at which an electric charge or heat F. Ionic Bond can pass through a material. G. Hardness 5. A property referring to the ability for a given substance, the solute, to dissolve in a solvent. E Learning Task 3: Draw a Venn Diagram of “Ionic vs Covalent Bonding”. Write down at least 5 words or phrases that will best describe the differences and similarities of the two types of bonding based on its properties. A Learning Task 4: Choose the letter of the correct answer. Write your answer on a separate sheet of paper. 1. The melting point of Sodium Fluoride (NaF) is 993˚C, while the Ammonia (NH 3) has -78˚C. Which of the following is the correct statement in determining these compounds? A. NaF – covalent; NH3 – ionic C. both are ionic B. NaF – ionic; NH3 – covalent D. both are covalent 2. The boiling point of Ethanol (C2H5OH) is 78˚C, while the Sodium Chloride (NaCl) has 1420˚C. Which of the following is the correct statement in determining these compounds? A. C2H5OH – covalent; NaCl – ionic C. both are ionic B. C2H5OH – ionic; NaCl – covalent D. both are covalent 3. A liquid substance “X” is poured and wet a piece of cloth in a room with a normal temperature. After leaving the cloth for a little amount of time, the cloth is dry. The substance may be determined as a/an___. A. Ionic compound C. Cannot be determined B. Covalent compound D. A type of salt PIVOT 4A CALABARZON Science G9 16  WEEK Formation of Ions 3 I Lesson In this lesson, we will be able to understand how ions are formed from their parent atoms, and learn to name them. Also, we will learn how the periodic table can help predict which ion a given element forms. Before running through the main topic, let’s have a trivia. Fig. 1 Light bulb powered by salt dissolved in water Did you know that you can use salt water to make a light bulb shine? It sounds crazy, but it's true! This is because salt water is a good conductor of electricity which makes ocean water a resource for renewable energy. Can you imagine how many light bulbs will be lighted, most especially here in our country, as an archipelago surrounded by oceans and seas having abundant saltwater? Also, a Filipina inventor, Engr. Aisa Mijeno, founded SALt or Sustainable Alternative Lighting as a way to generate energy and provide an alternative source of light to remote communities in the Philippines. SALt lamp is a LED lamp powered by the galvanic reaction of an anode with saline water. It can provide eight hours of light, as well as power to a USB port for charging a phone. The product concept was formed after living with the Butbut tribe for days relying only on kerosene lamps and moonlight to do evening chores. The saltwater serves not as the power source but as the electrolyte that facilitates the current flow within the metal-air battery. To understand why salt water conducts electricity, we have to first understand what electricity is. Electricity is a steady flow of electrons or electrically charged particles through a substance. In some conductors, such as copper, the electrons themselves are able to flow through the substance, carrying the current. In other conductors, such as salt water, the current is moved by molecules called ions. Pure water is not very conductive, and only a tiny bit of current can move through the water. When salt or sodium chloride (NaCl) is dissolved in it, however, the salt molecules split into two pieces, a sodium ion and a chlorine ion. The sodium ion is missing an electron, which gives it a positive charge. The chlorine ion has an extra electron, giving it a negative charge. Ions Any atom or molecule with a net charge, either positive or negative, is known as an ion. We can produce an ion, by taking a neutral atom and adding or removing one or more electrons. 17 PIVOT 4A CALABARZON Science G9  Ions are highly reactive species. They are generally found in a gaseous state and do not occur in abundance on Earth. Ions in the liquid or solid state are produced when salts interact with their solvents. They are repelled by like electric charges and are attracted to opposite charges. For example, in Figure 2, a sodium atom has 11 protons in its nucleus and eleven electrons outside its nucleus. 11 electrons If one of the electrons is lost, there will be eleven positive charges but only ten negative charges. This gives and ion with a net positive one (1+) charge: (11+) + (10-) = 1+. We can represent the process as follows: 11+ Fig. 2 NeuAtral Sodium atom (Na) Or in shorthand form, as Na → Na+ + e- A positive ion, called a cation (pronounces as cat’ eye on), is produced when one or more electrons are lost from a neutral atom. We have seen that sodium loses one electron to become a 1+ cation. A cation is named using the name if the parent atom (which is the Sodium, Na). Thus, Na+ is called the sodium ion (or sodium cation). When electrons are gained by a neutral atom, an ion with a negative charged is formed. A negatively charged ion is called an anion (pronounced an’ ion). An atom that gains one extra electron forms an anion with a 1- charge. An example of an atom that forms a 1- anion is the chlorine atom which has seventeen protons and seventeen electrons. Now, we can represent it as, Cl + e- → Cl- Note that the anion formed by chlorine has eighteen electrons but only seventeen protons so the net charge is (18-) + (17+) = 1-. PIVOT 4A CALABARZON Science G9 18 ASSIGNING NAMES FOR ANION Unlike a cation, which is named for the parent atom, an anion is named by taking the root name of the atom and changing the ending. For example, the Cl- anion produced from the Cl (chlorine) is obtained from the root of the atom name (chlor-) plus the suffix -ide. Other atoms that add one electron to form 1- ions include: fluorine F + e- → F- fluoride ion bromine Br + e- → Br- bromide ion iodine I + e- → I- iodide ion Note that the name of each of these anions is obtained by adding -ide to the root of the atom name. Some atoms can add two electrons to form 2- anions. Examples include: oxygen O + 2e- → O2- oxide ion sulfur S + 2e- → S2- sulfide ion Ion Charges and the Periodic table We find the periodic table very useful when we want to know what type of ion is formed by a given atom. Figure 3 shows the types of ions formed by atoms in several of the groups on the periodic table. Fig. 3 The ions formed by selected members of Groups 1, 2, 3, Note that the Group 1 metals all form 1+ ions (M+), the group 2 metals all form 2+ ions (M2+), and the group 3 metals form 3+ ions (M 3+). Thus, for Groups 1, 2, and 3, the charges of the cations formed are identical to the group numbers. In contrast to the Group 1, 2, and 3 metals, most of the transition metals from cations with various positive charges. For these elements, there is no easy way to pre- dict the charge of the cation that will be formed. Note that the metals always form positive ions. Nonmetals on the other hand, form negative ions by gaining electrons. Note that the Group 7 atoms all gain one electron to form 1- ions and that all the nonmetals in Group 6 gain two electrons for form 2- ions. Writing Chemical Formulas with Ions Many substances contain ions. In fact, whenever a compound forms between a metal and a nonmetal, it can be expected to contain ions. We call these substances ionic compounds. 19 PIVOT 4A CALABARZON Science G9  For example, note that the formula for sodium chloride is written NaCl, indication one of each type of these elements. This makes sense because sodium chloride contains Na+ ions and Cl- ions. Each sodium ion has a 1+ charge and each chloride ion has a 1- charge, so they must occur in equal numbers to give a net charge of zero. For any ionic compound, Total Charge + Total Charge = Zero net of Cations of Anions charge Consider and ionic compound that contains the ions Mg 2+ and Cl-. What combination of these ions will give a net charge of zero? To balance the 2+ charge on Mg2+, we will need two Cl- ions to give a net charge of zero. Cation Charge: Anion Charge Net Charge: 2+ + 2 x (1-) = 0 This means that the formula of the compound must be MgCl2. D Learning Task 2: Read each statement or question below carefully and fill in the blank(s) with the best answer by choosing the words inside the box. Write your answers in a separate sheet of paper. cation 1 -ide -ine nonmetals 0 ion ionic compound anion metals root name 1. Any atom or molecule with a net charge, either positive or negative, is known as an ___________. 2. An atom that gains one extra electron forms an ___________with a 1- charge. 3. A positive ion, called a __________ is produced when one or more electrons are lost from a neutral atom. 4. Unlike a cation, which is named for the parent atom, an anion is named by taking the ____________ of the atom and changing the ending. 5. The name of each anions is obtained by adding the suffix ____ to the root of the atom name. 6. The _________ always form positive ions. PIVOT 4A CALABARZON Science G9 20 7. _______________on the other hand, form negative ions by gaining electrons. 8. It is very important to remember that a chemical compound must have a net charge of ____________. E Learning Task 3: Answer the following questions below. Write your answer in a separate sheet of paper. Among the three pictures A, B, and C, which of the following will best represent: 1. An atom? Why? 2. A cation? Why? 3. An anion? Why? A B C A Read the following sentences. Rewrite in a separate sheet of paper. 1. It is important to recognize that ions are always formed by removing electrons from an atom (to form cations) or adding electrons (to form anions). Ions are never formed by changing the number of protons in an atom’s nucleus. 2. It is very important to remember that a chemical compound must have a net charge of zero. This means that if a compound contains ions, then a. There must be both positive ions (cations) and negative ions (anions) present. b. The numbers of cations and anions must be such that the net charge is zero. 21 PIVOT 4A CALABARZON Science G9 WEEKS The Structural Characteristics of Carbon 4-5 I Lesson Carbon isn’t a difficult element to spot in your daily life. For instance, if you’ve used a pencil, you’ve seen carbon in its graphite form. Similarly, the charcoal pieces on your barbeque are made out of carbon, and even the diamonds in a ring or necklace are a form of carbon (in this case, one that has been exposed to high temperature and pressure). What you may not realize, though, is that about 18% of your body (by weight) is also made of carbon. In fact, carbon atoms make up the backbone of many important molecules in your body, including proteins, DNA, RNA, sugars, and fats. The atomic number of carbon is 6, which represents the number of electrons. It is represented by the symbol C and is a non-metal. It has 6 protons, 6 neutrons and obviously 6 electrons. A carbon atom is considered to be special and unique because it can bond with other carbon atoms to an almost unlimited degree. It is because its atom is very small in size and can conveniently fit in as a part of larger molecules. Organic chemistry is an exceptionally important area of chemistry. The majority of chemicals occurring either naturally or synthetically are organic compounds. Essentially, organic chemistry is the chemistry of the element carbon. As a Group lV element, carbon has exceptional versatility when it comes to bonding, thus contributing to the vast number of organic compounds that occur naturally or can be produced synthetically. This lesson focuses on the bonding of carbon and some of the compounds carbon can form. History and Uses Carbon, the sixth most abundant element in the universe, has been known since ancient times. Carbon is most commonly obtained from coal deposits, although it usually must be processed into a form suitable for commercial use. Three naturally occurring allotropes of carbon are known to exist: amorphous, graphite and diamond. Amorphous carbon is formed when a material containing carbon is burned without enough oxygen for it to burn completely. This black soot, also known as lampblack, gas black, channel black or carbon black, is used to make inks, paints and rubber products. It can also be pressed into shapes and is used to form the cores of most dry cell batteries, among other things. Graphite, one of the softest materials known, is a form of carbon that is primarily used as a lubricant. Although it does occur naturally, most commercial graphite is produced by treating petroleum coke, a black tar residue remaining after the refinement of crude oil, in an oxygen-free oven. Naturally occurring graphite occurs in two forms, alpha and beta. These two forms have identical physical properties but different crystal structures. All artificially produced graphite is of the alpha type. In addition to its use as a lubricant, graphite, in a form known as coke, is used in large amounts in the production of steel. Coke is made by heating soft coal in an oven without allowing oxygen to mix with it. Although commonly called lead, the black material used in pencils is actually graphite. PIVOT 4A CALABARZON Science G9 22  Diamond, the third naturally occurring form of carbon, is one of the hardest substances known. Although naturally occurring diamond is typically used for jewelry, most commercial quality diamonds are artificially produced. These small diamonds are made by squeezing graphite under high temperatures and pressures for several days or weeks and are primarily used to make things like diamond tipped saw blades. Although they possess very different physical properties, graphite and diamond differ only in their crystal structure. A fourth allotrope of carbon, known as white carbon, was produced in 1969. It is a transparent material that can split a single beam of light into two beams, a property known as birefringence. Very little is known about this form of carbon. Large molecules consisting only of carbon, known as buckyballs, have recently been discovered and are currently the subject of much scientific interest. A single buckyball consists of 60 or 70 carbon atoms (C60 or C70) linked together in a structure that looks like a soccer ball. They can trap other atoms within their framework, appear to be capable of withstanding great pressures and have magnetic and superconductive properties. Carbon-14, a radioactive isotope of carbon with a half-life of 5,730 years, is used to find the age of formerly living things through a process known as radiocarbon dating. The theory behind carbon dating is fairly simple. Scientists know that a small amount of naturally occurring carbon is carbon-14. Although carbon-14 decays into nitrogen-14 through beta decay, the amount of carbon-14 in the environment remains constant because new carbon-14 is always being created in the upper atmosphere by cosmic rays. Living things tend to ingest materials that contain carbon, so the percentage of carbon-14 within living things is the same as the percentage of carbon-14 in the environment. There are nearly ten million known carbon compounds and an entire branch of chemistry, known as organic chemistry, is devoted to their study. Many carbon compounds are essential for life as we know it. Some of the most common carbon compounds are: carbon dioxide (CO2), carbon monoxide (CO), carbon disulfide (CS2), chloroform (CHCl3), carbon tetrachloride (CCl4), methane (CH4), ethylene (C2H4), acetylene (C2H2), benzene (C6H6), ethyl alcohol (C2H5OH) and acetic acid (CH3COOH). Why Carbon is Cool Carbon is so important because its atomic structure gives it bonding properties that are unique among elements. Each carbonmolecule has four unpaired electrons in its outer energy shell. Therefore, carbon atoms can form covalent bonds with up to four other atoms, including other carbon atoms. Carbon-based molecules have three fundamental structures—straight chains, branched chains, and rings. 23 PIVOT 4A CALABARZON Science G9  Straight Rings Branched Fig. 1 Three structures of carbon-based Carbon has a few unique bonding properties - the most important of which is its ability to form long chains of carbon. No other elements can do this. Silicon has the ability to theoretically do this, but silicon-oxygen bonds are so strong that silicon would much prefer to make Si - O - Si bonds than silicon-silicon bonds. The reason carbon can do this is that carbon-carbon bonds are extremely strong. This allows carbon to make up many of the basic building blocks of life (fats, sugars, etc). Also, because carbon makes four bonds, it is able to exist in many different forms called isomers. No other element naturally does this as much as carbon. Fig. 2 Carbon chains can bond with carbon rings to form four covalent bonds. Bonding of Carbon with itself: Allotropy Allotropy is a behavior exhibited by certain chemical elements: these elements can exist in two or more different forms, known as allotropes of that element. When an element exists in more than one crystalline form, those forms are called allotropes. In each different allotrope, the element's atoms are bonded together in a different manner. Allotropes are different structural modifications of an element. Carbon is an element that exhibits allotropy. Some of its allotropes are shown below: Fig. 3 Carbon allotropes; a) diamond; b) graphite; c) lonsdaleite; d-f) buckballs (C60, C540, C70); g) amorphous carbon; h) carbon nanotube. PIVOT 4A CALABARZON Science G9 24  The physical properties of this element vary according to its allotropes. The two major allotropes are diamond and graphite. These two have almost opposing physical properties. Diamond Graphite  Whereas diamond is transparent and has no color, graphite is opaque and black.  Diamond is the hardest substance known to man, graphite is soft and spongy in texture.  Now diamond cannot conduct electricity at all, graphite is a very good conductor of electricity.  Both allotropic elements are solid, non-gaseous.  Also, both diamond and graphite are insoluble in water. Lewis Dot Structure The carbon atom has six electrons, of which four are available for bonding. To reach electronic stability, carbon atoms must share four electrons from other atoms. (The gaining or losing of four electrons requires too much energy in such a small atom). Carbon, therefore, forms four (two-electron) bonds to other atoms, which may be single (one shared pair), double (two shared pairs) or triple (three shared pairs). Lew is Dot St ruc t ur e a nd Molecular Models for Methane (the simplest alkane): Table 1: An illustration of how the shape of the molecule changes as additional –CH2 subunits are added vs. losing a pair of H’s each time an additional C-C bond is added to form double or triple bonds. 25 PIVOT 4A CALABARZON Science G9 Carbon chains form the skeletons of most organic molecules. Carbon chains also vary in length and shape. Below are the examples of carbon chains in different orientations: Straight Chain Alkanes See below for the table that gives the names of the straight chain alkanes. The general formula for an alkane is CnH2n+2 where n is the number of carbon atoms in the molecule. There are two ways of writing a condensed structural formula. For example, butane may be written as CH3CH2CH2CH3 or CH3(CH2)2CH3. # Carbon Name Molecular Structural Formula Formula 1 Methane CH4 CH4 2 Ethane C2H6 CH3CH3 3 Propane C3H8 CH3CH2CH3 4 Butane C4H10 CH3CH2CH2CH3 5 Pentane C5H12 CH3CH2CH2CH2CH3 6 Hexane C6H14 CH3(CH2)4CH3 7 Heptane C7H16 CH3(CH2)5CH3 8 Octane C8H18 CH3(CH2)6CH3 9 Nonane C9H20 CH3(CH2)7CH3 10 Decane C10H22 CH3(CH2)8CH3 n CnH2n+2 PIVOT 4A CALABARZON Science G9 26  D Learning Task 1: Determine what kind of carbon allotropes are the given pictures below based on its different structural modifications. Write your answer in a separate sheet of paper. E Learning Task No. 2: Draw the shape of the three fundamental structures of carbon- based molecules (straight chains, rings, and branched chains). After that, draw one thing that resembles the said structures that you commonly see in your daily lives. Draw your answer in a separate sheet of neat paper. Example: Carbon-based molecule structure - Rings Flower Crown Note: The flowers and leaves represent the Carbon and Hydrogen atoms while the branches are the chains A Learning Task 3: Given the value of n, write the names and molecular formulas of straight chain alkanes. General Formula: CnH2n+2 1. If n = 2, Name? b. Molecular Formula? 2. If n = 4, Name? b. Molecular Formula? 3. If n = 5, Name? b. Molecular Formula? 4. If n = 7, Name? b. Molecular Formula? 5. If n = 9, Name? b. Molecular Formula? 27 PIVOT 4A CALABARZON Science G9 WEEK Organic Compounds 6 I Lesson The chemical compounds of living things are known as organic compounds because of their association with organisms and because they are carbon-containing compounds. Organic compounds, which are the compounds associated with life processes, are the subject matter of organic chemistry. Let us take a look at the pictures below. Which are considered organic? Which are not? Do you have a clue? What is Organic? All of the objects are considered organic except the rocks and the house. To a chemist, the term organic describes chemical compounds that contain carbon and other elements such as hydrogen, oxygen, nitrogen, sulfur, or phosphorus. For example, sugar was identified as organic. Why is sugar organic? The chemical formula for sugar is C6H12O6. The compound contains carbon, hydrogen, and oxygen. Sugar is processed from sugar cane, a plant. All living organisms contain carbon- based compounds, making them organic. At the grocery store, the term organic describes foods raised under specific conditions. For example, beef labeled organic is from cows that were not given antibiotics, growth hormones, or fed animal by-products. All of the organisms pictured are alive and composed of organic compounds. What do you observe? As shown below, two columns are divided – one is for organic compounds and the other is for inorganic compounds. What did you notice about all the compounds that are classified as examples of organic compounds? PIVOT 4A CALABARZON Science G9 28  Did you observe carbon is always present and that hydrogen and oxygen are commonly found in organic compounds? Great! Most organic compounds contain carbon, hydrogen, and sometimes other elements such as nitrogen, sulfur, oxygen, or phosphorus. All living organisms contain carbon—even bacteria. Our bodies are composed mostly of water, H2O, and it is necessary for us to survive. However, water is an example of an inorganic compound because it does not contain carbon and it was not formed by a living organism. Carbon dioxide, CO2, is another example of an inorganic compound because it does not contain both carbon and hydrogen. One molecule of CO 2 contains one atom of carbon and two atoms of oxygen. There are a total of three atoms in one molecule of carbon dioxide, CO2. General Classes of Organic Compounds and Its Uses A while ago, we knew that organic compounds are called "organic" because they are associated with living organisms. These molecules form the basis for life and are studied in great detail in the chemistry disciplines of organic chemistry and biochemistry. Most of the foodstuffs that we consume every day such as sugar, fats, starch, vinegar, etc. are basically organic compounds. Even though the organic compounds have been known to man since prehistoric times, their study practically began from the eighteenth century! The term “organic compound” was coined by Jöns Jakob Berzelius in 1807. There are four main types, or classes, of organic compounds found in all living things: carbohydrates, lipids, proteins, and nucleic acids. In addition, there are other organic compounds that may be found in or produced by some organisms. All organic compounds contain carbon, usually bonded to hydrogen (other elements may be present as well). Let's take a closer look at the key types of organic compounds and see examples of these important molecules. Let’s explore more about these compounds. Carbohydrates Carbohydrates are organic compounds made of the elements carbon, hydrogen, and oxygen. The ratio of hydrogen atoms to oxygen atoms in carbohydrate molecules is 2:1. Organisms use carbohydrates as energy sources, structural units, and for other purposes. Carbohydrates are the largest class of organic compounds found in organisms. Carbohydrates are classified according to how many subunits they contain. Simple carbohydrates are called sugars. A sugar made of one unit is a monosaccharide (glucose, fructose, galactose). If two units are joined together, a disaccharide is formed. A polysaccharide is a long chain of monosaccharides joined together (starch, glycogen, cellulose). The functions of carbohydrates are: 1. It acts as a main source of energy. 2. Plants and animals use it for structural purposes. Lipids Lipids are made of carbon, hydrogen, and oxygen atoms. Lipids have higher hydrogen to oxygen ratio than is found in carbohydrates. The three major groups of lipids are triglycerides (fats, oils, waxes), steroids, and phospholipids. 29 PIVOT 4A CALABARZON Science G9  Certain fatty acids have one or more double bonds in their molecules. Fats that include these molecules are unsaturated fats. Other fatty acids have no double bonds. Fats that include these fatty acids are saturated fats. In most human health situations, the consumption of unsaturated fats is preferred to the consumption of saturated fats. Saturated fats are solid at room temperature and bad for you, while unsaturated fats are liquid at room temperature and are better for you. Fats stored in cells usually form clear oil droplets called globules because fats do not dissolve in water. Plants often store fats in their seeds, and animals store fats in large, clear globules in the cells of adipose tissue. Lipids are used for energy storage, to build structures, and as signal molecules to help cells communicate with each other. The functions of lipids are: 1. Store energy for long term 2. Waterproof covering Proteins Proteins consist of chains of amino acids called peptides. A protein may be made from a single polypeptide chain or may have a more complex structure where polypeptide subunits pack together to form a unit. Proteins consist of hydrogen, oxygen, carbon, and nitrogen atoms. Some proteins contain other atoms, such as sulfur, phosphorus, iron, copper, or magnesium. Proteins serve many functions in cells. They are used to build structure, catalyze biochemical reactions, for immune response, to package and transport materials, and to help replicate genetic material. The functions of proteins are: 1. Cellular structures 2. Controls substances in and out of cell 3. Fight diseases Examples of Proteins are: 1. Hemoglobin in blood 4. Insulin 7. Myoglobin 2. Collagen 5. Keratin 8. Fibrin Nucleic Acid Nucleic acids are the molecules in our cells that direct and store information for reproduction and cellular growth. There are two types of nucleic acids: 1. Ribonucleic Acid (RNA) 2. Deoxyribonucleic Acid (DNA) Both nucleic acids are unbranched organic polymers composed of monomer units called nucleotides. These nucleotides are composed of a sugar molecule, a nitrogen base, and phosphoric acid. A single DNA molecule may contain several million of these nucleotides, while the smaller RNA molecules may contain several thousand. PIVOT 4A CALABARZON Science G9 30  The DNA carries the genetic information for the cells. Sections of a DNA molecule called genes contain the information to make a protein. DNA serves two main functions. Molecules of DNA can produce other DNA molecules and RNA molecules. RNA molecules are directly responsible for the synthesis of proteins. D Learning Task 1: Choose the letter of the correct answer. Write your answers on a separate sheet of paper. 1. Organisms use ____________ as energy sources, structural units, and for other purposes and are the largest class of organic compounds found in organisms. A. carbohydrates B. lipids C. protein D. nucleic acid 2. _____________ are the molecules in our cells that direct and store information for reproduction and cellular growth. A. carbohydrates B. lipids C. protein D. nucleic acid 3. _____________ are used for energy storage, to build structures, and as signal molecules to help cells communicate with each other. A. carbohydrates B. lipids C. protein D. nucleic acid 4. They are used to build structure, catalyze biochemical reactions, for immune response, to package and transport materials, and to help replicate genetic material. Learning Task 2: Write in the space provided if the given examples or statements are classified as carbohydrate, lipid, protein or nucleic acid. _________________ 1. Sugar cubes _________________ 2. Wheat bread _________________ 3. A melted butter. _________________ 4. Ribonucleic Acid _________________ 5. Virgin Coconut Oil _________________ 6. Deoxyribonucleic Acid _________________ 7. Hair and nails that contain keratin _________________ 8. An insulin needed by a diabetic patient _________________ 9. Sweet extracted juice from fresh pineapple _________________ 10. Earwax that protects insides of human ears A Draw 3 examples of lipids found at home. Do this in a separate sheet of paper. 31 PIVOT 4A CALABARZON Science G9 WEEK The Mole 7 Lesson I Medicines are chemicals or compounds used to cure, halt, or prevent disease; ease symptoms; or help in the diagnosis of illnesses. Advances in medicines have enabled doctors to cure many diseases and save lives. These days, medicines come from a variety of sources. Many were developed from substances found in nature, and even today many are extracted from plants. Some medicines are made in labs by mixing together a number of chemicals. Others, like penicillin, are byproducts of organisms such as fungus. And a few are even biologically engineered by inserting genes into bacteria that make them produce the desired substance. When we think about taking medicines, we often think of pills. But medicines can be delivered in many ways, such as: a. liquids that are swallowed b. drops that are put into ears or eyes c. creams, gels, or ointments that are rubbed onto the skin d. inhalers (like nasal sprays or asthma inhalers) e. patches that are stuck to skin (called transdermal patches) f. tablets that are placed under the tongue (called sublingual medicines; the medicine is absorbed into blood vessels and enters the bloodstream) g. injections (shots) or intravenous (inserted into a vein) medicines But, how do we form the rightful amount of medicine that we need? In order to make the drug form its ingredients, someone has to figure out how much of each ingredient is needed to react together to make the final drug. This will prevent us from having drug overdose, or taking too much from a substance which can result to abnormal breathing, loss of consciousness, and worse may lead to death. This concept also applies in manufacturing of plastics. Since plastics are made from other chemicals, someone has to figure out how much of each ingredient is needed to use. Same goes while you light a bonfire, in which you can determine how much air is needed, how much exhaust will be produced, as well as how much heat is created. To medicines, plastics, and even burning pieces of wood require right amount of substances that will produce one. But how do we measure those small entities? All these examples have involved using the concept of moles. In this lesson, we will be able to understand the mole concept and Avogadro’s number. Also, we will be able to learn conversion among moles, mass and number of atoms in a given sample. The Mole The identity of a substance is defined not only by the types of atoms or ions it contains, but by the quantity of each type of atom or ion. For example, water, H2O, and hydrogen peroxide, H2O2, are alike in that their respective molecules are composed of hydrogen and oxygen atoms. However, because a hydrogen peroxide molecule contains two oxygen atoms, as opposed to the water molecule, which has only one, the two substances exhibit very different properties. These traits were originally derived from the measurement of macroscopic properties (the masses and volumes of bulk quantities of matter) using relatively simple tools (balances and PIVOT 4A CALABARZON Science G9 32 volumetric glassware). This experimental approach required the introduction of a new unit for amount of substances, the mole, which remains indispensable in modern chemical science. The mole (abbreviated mol) is a fundamental unit of measurement of substances and can be defined as the number equal to the number of carbon atoms in 12.01 grams of carbon. A mole is also the atomic or formula mass of a substance expressed in grams. Techniques for counting atoms very precisely have been used to determine this number to be 6.022 x 1023. This number is called Avogadro’s number. One mole of something consists of 6.022 x 1023 units of that substance. Just as a dozen of eggs is 12 eggs, a mole of eggs is 6.022 x 10 23 eggs. Just like a mole of water contains 6.022 x 1023 H2O molecules. Example: How many molecules are there in 4.0 moles of CO 2? To answer this question, remember that, 1 mole = 6.022 x 1023 particles Thus, using the dimensional analysis approach, you will be able to convert number of moles to its equivalent amount in the number of particles. Calculating Moles and Number of Atoms How do we use the mole in chemical calculations? Recall that Avogadro’s number is defined such that a 12.01-g sample of carbon contains 6.022 x 1023 atoms. Let’s take a look at the step-by-step procedure below. Fig. 2 A bicycle with an aluminum Aluminum (Al), a metal with a high strength-to-weight ratio and a high resistance to corrosion, is often used for structures such as high-quality bicycle frames. Compute both the number of moles of atoms and the number of atoms in a 10.0-g sample of aluminum. Solution In this case we want to change from mass to moles of atoms: ? moles 10.0 g of Al Al atoms The mass of 1 mol (6.022 x 1023 atoms) of aluminum is 26.98 g (Note: You can get the value 26.98 g by seeing the atomic mass of Aluminum in the Periodic Table of Elements). The sample we are considering has a mass of 10.0 g. Its mass is less than 26.98 g, so this sample contains less than 1 mol of aluminum atoms. We calculate the number of moles of aluminum atoms in 10.0g by using the equivalence statement 1 mol Al = 26.98 g Al 33 PIVOT 4A CALABARZON Science G9  To construct the appropriate conversion factor: 10.0 g Al x = 0.371 mol Al Next, we will convert from moles of atoms to the number of atoms, using the equivalence statement 6.022 x 1023 Al atoms = 1 mol of Al atoms 0.371 mol Al x 6.022 x 1023 Al atoms = 2.23 x 1023 Al Atoms 1mol Al We can summarize this calculation as follows: 10.0 g Al x 0.371 mol Al 0.371 mol 6.022 x 1023 Al atoms 2.23 x 1023 x = Al atoms 1mol Al Al Atoms Calculating Molar Mass of a Compound In this part of our lesson, we will be able to understand the definition of molar mass and also, we will be able to learn how to convert between moles and mass of a given sample of a chemical compound. A chemical compound is, fundamentally, a collection of atoms. For example, methane (the major component of natural gas) consists of molecules each containing one carbon atom and four hydrogen atoms (CH4). How can we calculate the mass of 1 mol of methane? Or, what is the mass of 6.022 x 10 23 CH4 molecules? Because each CH4 molecules contains one carbon atom and four hydrogen atoms, 1 mol of CH4 molecules consists of 1 mol of carbon atoms and 4 mol of hydrogen atoms, as shown in Figure 3. The mass of 1 mol of methane can be found by summing the masses of carbon and hydrogen present: Solution Methane = CH4 = 1 C atom + 4 H atoms Atomic Mass of C = 1 x 12.01 g/mol = 12.01 g/mol Atomic Mass of H = 4 x 1.008 g/mol = 4.032 g/mol (add) Molar Mass of CH4 = 16.04 g/mol PIVOT 4A CALABARZON Science G9 34  1 mol C atoms (6.022 x 10²³ C atoms) 1 mol CH₄ molecules (6.022 x 10²³CH₄ molecules 4 mol H atoms 4 (6.022 x 10²³ H atoms) Fig. 3 Various numbers of methane molecules showing their constituent atoms The quantity 16.04 g/mol is called the molar mass for methane: the mass of 1 mol of CH4 molecules. The molar mass of any substance is the mass (in grams) of 1 mol of the substance. The molar mass is obtained by summing the masses of the component atoms. Example: Calculate the molar mass of sulfur dioxide, a gas produced when sulfur containing fuels are burned. Unless “scrubbed” from the exhaust, sulfur dioxide can react with moisture in the atmosphere to produce acid rain. Solution The chemical formula for sulfur dioxide is SO2. We need to compute the mass of 1 mol of SO2 molecules – the molar mass of sulfur dioxide. We know that 1 mol of SO2 molecules contains 1 mol of sulfur atoms and 2 mol of oxygen atoms. (Note: You can get the value 32.07 g and 16.00 g by seeing the atomic mass of Sulfur and Oxygen in the Periodic Table of Elements). 1 mol S atoms 1 mol of SO2 mole- cules 2 mol O atoms 35 PIVOT 4A CALABARZON Science G9  Atomic Mass of S = 1 x 32.07 g/mol = 32.07 g/mol Atomic Mass of O = 2 x 16.00 g/mol = 32.00 g/mol (add Molas mass of SO2 = 64.07 g/mol Example: Calculate the molar mass, number of moles and the number of particles present in 50.0 g of iron(III) oxide, Fe2O3 (rust). Solution The chemical formula is Fe2O3. We need to compute the mass of 1 mol of Fe2O3 molecules – the molar mass of iron(III) oxide. We know that 1 mol of Fe 2O3 molecules contains 2 mol of Fe atoms and 3 mol of O atoms. (Note: You can get the value 55.85 g and 16.00 g by seeing the atomic mass of Iron and Oxygen in the Periodic Table of Elements). 2 mol Fe atoms 1 mol of Fe2O3 molecules 3 mol O atoms For molar mass: Atomic Mass of Fe = 2 x 55.85 g/mol = 111.7 g/mol Atomic Mass of O = 3 x 16.00 g/mol = 48.0 g/mol (add) Molar Mass of Fe2O3 = 159.7 g/mol For number of moles (of a 50.0 g Fe2O3): 1 mol of Fe2O3 = 159.7 g To construct the appropriate conversion factor: 1 mol of Fe2O3 50.0 g Fe2O3 x = 0.313 mol of Fe2O3 159.7 g Fe2O3 For number of particles: (Note: Finding the number of “particles” means finding the number of “atoms”.) We will convert from moles of atoms to the number of atoms, using the equivalence statement 6.022 x 1023 Fe2O3 atoms = 1 mol of Fe2O3 atoms 6.022 x 1023 Fe2O3 atoms 0.313 mol Fe2O3 x = 1.88 x 1023 1 mol Fe2O3 Fe2O3 atoms PIVOT 4A CALABARZON Science G9 36  D Learning Task 1: For you to have a feel on how it is being done, you may answer the following questions below. 1. How many mongo seeds are equal to 3.50 moles of mongo seeds? 2. How many bananas are equal to 7.50 moles of bananas? 3. How many moles of rice grains are equal to 1.807 x 1024 grains of rice? E Learning Task 3: Solve the following problems below. Do this in a separate sheet of paper. 1. Gold (Au) has been used to make ornamental objects and jewelry for thousands of years. Gold nuggets found in a stream are very easy to work and were probably one of the first metals used by humans. (1 mol of Gold (Au) = 196.97g). Calculate the: A. Number of moles in a 95.0 g sample of a gold nugget. B. Number of atoms in a 95.0 g sample of a gold nugget. 2. During exercise, lactic acid (C3H6O3) forms in the muscles causing muscle cramp. If 5.0 g of lactic acid (C3H6O3) concentrate in your leg muscles, how many molecules of lactic acid is causing you pain? (C = 12.0 g/mol, H = 1.008 g/mol, O = 16.0 g/mol) A Read the sentence. Add one sentence related to the content. Write this in a separate sheet of paper. Stoichiometry is calculation of the amount (mass, moles, particles) of one substance in the chemical equation from another. _____________________________________________________________________ ___________________________________________________________________. 37 PIVOT 4A CALABARZON Science G9 WEEK Percent Composition of Compounds 8 I Lesson Supposed that you had your 2nd periodical examination in Science. When you get a score of 85% in the said test, what does it mean? It means that, if there are 100 items in your test, 85% means you answered 85 items correctly. To have another example, let us talk about the Baker’s Percentage. When writing a recipe (formula), Baker’s Percentage, Baker's Percent, Flour Weight, or Baker’s Math is a way to express the ratio of ingredients to one another by weight. Baker’s % is internationally used to express formulas for baked products such as bread, cookies, cakes, scones, and most any product where flour is the primary ingredient. Each ingredient in a formula is expressed as a percentage of the largest ingredient, usually the flour weight, always expressed as 100%. BAKER’S % Key IDEA: The MATH: This is not percentage as you learned in In just two simple steps. school. Forget about pie charts and think bars instead. 1. Pick amount of flour: 500g Remember: Flour —100% This is the 100% Water —70% 2. Use flour amount to calculate weights Salt —2% for other ingredients: Yeast —1:% 500g x 70% = 350g 500g x 2% = 10g 500g x 1% = 5g Fig. 1 Baker’s Percentage The advantage of this system is that it allows for the baker to easily convert their recipe into different weight indicators, such as pounds, ounces, kilograms, or grams. And once all of the weights of the ingredients in the recipe are calculated, it is By looking at percentages, it is easier to tell if one recipe is drier, sweeter, saltier, etc. than another recipe. It also makes predicting what the final product will look like easier. Baker’s % can be used to quickly and easily convert between batch sizes as well. We knew how dividing the right amount of ingredients can produce a bread that has flavorful taste. Going further in this lesson, we will talk about Percentage. Percent indicates parts per hundred. In chemistry, it is commonly used to find the mass percent of an element in a given compound. Look at the example found on the next page. Part Percent = x 100% Percent = x 100% Whole PIVOT 4A CALABARZON Science G9 38  Example: There are 200 apples. 30 apples are considered bad and will be not for sale. How many percent of apples are bad? Percentage Composition of Compounds In the laboratory, you may perform experiments that will require you to prepare solutions or to verify the purity of some substances. If you are asked to prepare a 10% salt solution, you dissolve 10g of salt in a 90g of water to make a 100g salt solution. Thus, you need to know how to calculate the percent compositions of compounds. Mass of element % Mass percent = x 100% Mass of compound The mass fraction is converted to mass percent by multiplying 100%. We will illustrate this concept using the compound ethanol, an alcohol obtained by fermenting the sugar in grapes, corn, and other fruits and grains. Ethanol (C 2H6O -) is often added to gasoline as an octane enhancer to form a fuel called gasohol. The added ethanol has the effect of increasing the octane of the gasoline and also lowering the carbon monoxide in automobile exhaust. Note from its formula that each molecule of ethanol contains two carbon atoms, six hydrogen atoms, and one oxygen atom. This means that each mole of ethanol contains 2 mol of carbon atoms, 6 mol of hydrogen atoms, and 1 mol of oxygen atoms. We calculate the mass of each element present and the molar mass for ethanol as follows: Atomic Mass of C = 2 x 12.01 g/mol = 24.02 g/mol Atomic Mass of H = 6 x 1.008 g/mol = 6.048 g/mol Atomic Mass of O = 1 x 16.00 g/mol = 16.00 g/mol (add) Molar Mass of C2H6O = 46.07 g/mol The mass percent (sometimes called the weight percent) of carbon in ethanol can be computed by comparing the mass of carbon in 1 mol of ethanol with the total mass of 1 mol of ethanol and multiplying the result by 100%. mass of C in 1 mol C2H6O Mass percent of C = x 100% mass of 1 mol C2H6O 24.02 g = x 100% = 52.14% 46.07 g That is, ethanol contains 52.14% by mass of carbon. The mass of percent of hydrogen and oxygen in ethanol are obtained in a similar manner. mass of H in 1 mol C2H6O Mass percent of H = x 100% mass of 1 mol C2H6O 6.048 g = x 100% = 13.13% 46.07 g 39 PIVOT 4A CALABARZON Science G9  mass of O in 1 mol C2H6O Mass percent of O = x 100% mass of 1 mol C2H6O 16.00 g = x 100% = 37.43% 46.07 g The mass percents of all the elements in a compound add up to 100%, although rounding-off effects may produce a small deviation. Adding up the percentages is a good way to check the calculations. In this case, the sum of the mass percent's is 52.14% + 13.13% + 34.73% = 100.00%. D Learning Task 1: Calculate the mass percent of each element in a compound. Write your solution in a separate sheet of paper. Calculate the percent by mass of each element in the following compounds: 1. Methane, CH4 (C = 12.01 g/mol; H = 1.008 g/mol) 2. Sodium Nitrate, NaNO3 (Na = 23.0 g/mol; N = 14.0 g/mol; O = 16.0 g/mol) E Learning Task 3: Calculate the percent mass of each element of a compound NaHSO3 (Na = 23.o g/mol; H = 1.008 g/mol; S = 32.0 g/mol; O = 16.0 g/mol). After getting the percent mass, divide the circle to the computed percentage of each corresponding element. (Note that the circle is equivalent to 100% as a whole; you can use several colors to represent each percent mass of the elements.) 1. Based on your circle, which element has the biggest mass percent? 2. Which has the smallest mass percent? A Describe or express your simpliest technique in solving problems found in D & E part of the lesson. Write your answer in a separate sheet of paper. PIVOT 4A CALABARZON Science G9 40 PIVOT 4A CALABARZON Science G9 41 Learning Task 3: 1(a.) Mass of C in 1 mol = 1 mol x 12.01 g/mol = 12.01g Learning Task 1: Mass of H in 1 mol = 4 mol x 1.008 g/mol = 4.032 g 1. 2.107 x 1024 mongo seeds (add) 2. 4.515 x 1024 bananas 3. 3 grains of rice Molar Mass = 16.032 g Mass Percent of C = (12.01g/16.032g) x 100% = 74.91% Learning Task 2: Mass Percent of H = (4.032g/16.032g) x 100% = 25.15% 1. a. 0.482 mol Au b. 2.9 x 1023 Au atoms 2. C = 3 x 12 = 36 H = 6 x 1.008 = 6.048 O = 3 x 16 = 48 WEEK 8 WEEK 7 Learning Learning Task 1: Learning Learning Task 2: Learning Task 3: Task 3: Task 1: 1. B 3. A 5. B 1. Saturated 2. B 4. D a. Ethane b. C2H6 1. Buckballs C70 2. Unsaturated a. Butane b. C4H10 2. Buckballs Learning Task 2: C60 3. Saturated 1.Carbohydrates 6. Nucleic Acid a. Pentane b. C5H12 3.Lonsdaleite 2. Carbohydrates 7. Protein 4. Graphite 4. Saturated a. Heptane b. C7H16 3. Lipid 8. Protein 5. Diamond 5. Unsaturated 4. Nucleic Acid 9.Carbohydrates 6.Amorphous a. Nonane b. C9H20 5. Lipid 10. Lipid Carbon WEEK 6 WEEKS 4-5 Learning Task 3 Learning Task 2: Learning Task 1: A, anions have more electrons 1. Ion than protons. 2. Anion B. atoms have equal numbers 3. Cation of protons and electrons. 4. Root name C, cations have more protons 5. -ide than electrons. 6. Metals 7. Nonmetals 8. 0 WEEK 3 Learning Task 2: Learning Task 1: Learning Task 1: 1. True 1. C 3. B 5. B 1. H 3. L 5. J 2. False; p-orbital 2. 2. A 4. B 2. M 4.C 3.False; 0, 1, 2, 3, and 4 only 4. True Learning Task 4: Learning Task 3: 5.False; 5 boxes, 10 electrons 1. B, Learning Task 3: 2. A, 1. a. Principal quantum number 3. B b.Angular momentum quantum number c. Magnetic quantum number d. Spin quantum number 2. 0, 1, 2, 3, 4, 5 3. -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5 4. n = 9 WEEK 2 WEEK 1 Key to Correction  Personal Assessment on Learner’s Level of Performance Using the symbols below, choose one which best describes your experience in working on each given task. Draw it in the column for Level of Performance (LP). Be guided by the descriptions below. - I was able to do/perform the task without any difficulty. The task helped me in understanding the target content/lesson. - I was able to do/perform the task. It was quite challenging but it still helped me in understanding the target content/lesson. - I was not able to do/perform the task. It was extremely difficult. I need additional enrichment activities to be able to do/perform this task. Distribution of Learning Tasks Per Week for Quarter 2 Week 1 LP Week 2 LP Week 3 LP Week 4 LP Learning Task 1 Learning Task 1 Learning Task 1 Learning Task 1 Learning Task 2 Learning Task 2 Learning Task 2 Learning Task 2 Learning Task 3 Learning Task 3 Learning Task 3 Learning Task 3 Learning Task 4 Learning Task 4 Learning Task 4 Learning Task 4 Learning Task 5 Learning Task 5 Learning Task 5 Learning Task 5 Learning Task 6 Learning Task 6 Learning Task 6 Learning Task 6 Learning Task 7 Learning Task 7 Learning Task 7 Learning Task 7 Learning Task 8 Learning Task 8 Learning Task 8 Learning Task 8 Week 5 LP Week 6 LP Week 7 LP Week 8 LP Learning Task 1 Learning Task 1 Learning Task 1 Learning Task 1 Learning Task 2 Learning Task 2 Learning Task 2 Learning Task 2 Learning Task 3 Learning Task 3 Learning Task 3 Learning Task 3 Learning Task 4 Learning Task 4 Learning Task 4 Learning Task 4 Learning Task 5 Learning Task 5 Learning Task 5 Learning Task 5 Learning Task 6 Learning Task 6 Learning Task 6 Learning Task 6 Learning Task 7 Learning Task 7 Learning Task 7 Learning Task 7 Learning Task 8 Learning Task 8 Learning Task 8 Learning Task 8 Note: If the lesson is designed for two or more weeks as shown in the eartag, just copy your personal evaluation indicated in the first Level of Performance in the second column up to the succeeding columns, i.e. if the lesson is designed for weeks 4-6, just copy your personal evaluation indicated in the LP column for week 4, week 5 and week 6. PIVOT 4A CALABARZON Scienc