Science Unit One Matter PDF

Science Unit One Matter Lesson 1: Atomic Structure Lesson 2: Periodic table for classifying elements Lesson 3: Matter and its characteristics Lesson 4: Chemical Bonds 1  UNIT 1: Matter Lesson One: Atomi...

Science Unit One Matter Lesson 1: Atomic Structure Lesson 2: Periodic table for classifying elements Lesson 3: Matter and its characteristics Lesson 4: Chemical Bonds 1  UNIT 1: Matter Lesson One: Atomic Structure Matter: It is anything has mass and volume. OR It's anything has mass and occupies a space. * Matter consists of molecules Atom is the fundamental building unit of matter * The figure shown represents the Sphinx Matter : Sphinx Molecules: Limestone rocks (Calcium carbonate) CaCO3 Atoms Calcium Carbon 3 Oxygen Building of Atom 2 Scientists have made numerous attempts to discover the structure of the atom. Greek philosophers in ancient times believed that matter was made up of small, indivisible parts called atoms. Then In the early 19th century, the scientist Dalton developed the first scientific theory about the atom, in which he stated that atoms are indivisible. Then Rutherford's model of the atom (1909 AD) is considered the first experimental model of the atom. Scientists have determined the structure of the atom as follows: Subatomic Structure: Nucleus Electrons Negatively charged particles with A very, very small space located at very little mass that revolve around the center of the atom. It contains the nucleus at high speeds in two types of particles: energy levels. o Protons: Positively charged Protons, neutrons, and electrons particles. are considered subatomic particles. o Neutrons: Neutral particles (no charge). Measurement and Scale If we represent the size of an atom as the size of a baseball field, the size of the nucleus would be comparable to the size of the head of a pin in the middle of the field. 3  Give reason: the nucleus has positive charge. Bec. It contains positive protons and neutral neutrons. A Brief Biography of a Scientist Ernest Rutherford, the Scientist: -He is a New Zealand scientist, born in 1871 A.C. -He was awarded the Nobel Prize in Chemistry in 1908 and passed away in 1937. -New Zealand honored him by placing his image on currency due to his highest denomination in recognition of his efforts in discovering the structure of the atom. Properties of Subatomic Particles That Make Up the Atom The atom is made up of three types of small particles, which differ from each other in symbol and electric charge and mass. Relative charge U U 1/ 1836 U From the previous table, we can conclude that: 4 1. The magnitude of charge of a proton is = to the magnitude charge of an electron, but differs in type. 2. The masses of subatomic particles are measured in atomic mass units ( U ). 3. The mass of electrons is negligible compared to the mass of protons or neutrons. Give reason: 1) The mass of the atom is concentrated in the nucleus. Bec. the mass of electrons is negligible compared to the mass of protons or neutrons within the nucleus. 2) Scientists have agreed to represent elements using chemical symbols. To facilitate their expression and handling, especially in chemical equations. 5 Examples of elements which have Latin name 6  Life application Fertilizers are chemical compounds used to improve agricultural crop. NPK fertilizer is one of the most important types of fertilizers. Fertilizers are composed of three compounds containing these elements. Fertilizers contain elements such as: necessary for the greening NPK fertilizer Nitrogen of plant leaves. helps strengthen plant Phosphorous roots. essential for healthy plant Potassium growth. 7  The Relationship Between the Numbers of Subatomic Particles: Mass number A(number of nucleons): the sum of number of positive protons(P) and number of neutral neutrons(n) in the nucleus. Atomic number z: the number of positive protons. Or the number of negative electrons(e-) Number of neutrons = mass number – atomic number A = p + n Z = p = e- n= A– Z number of neutrons may be equal to or greater than number of protons. 4 7 2 He 3 Li Train your brain Complete the following: 1- In the nucleus of an atom, the number of................................. is usually greater than or equal to the number of protons. 2- The element..........................................is necessary for strengthening roots, while the element.....................................is necessary for the healthy growth of plants. 3- The ratio of the mass of an electron to the mass of a proton is……………………. one. 4- Protons are ……………………………. charged particles, while……………………….are negatively charged particles that orbit the nucleus. 8  Electronic Configuration Electrons orbit the nucleus in specific paths called energy levels. Energy Levels Imaginary regions where electrons orbit the nucleus, each according to its energy. - The number of main energy levels is seven main levels. - The energy level is denoted by the symbol (n) and is represented by the letters (K, L, M, N,O,P,Q ) Energy of level K : lowest energy. Q: highest energy. Q > P >O >N > M > L >K - The energy of electron is the same energy of its level. - As the electron moves farther from the nucleus, its energy increases, and as it gets closer to the nucleus, its energy decreases. - Each main energy level consists of a specific number of sub-levels, where electrons orbit in different shapes. 9  Rules of Distributing Electrons in Energy Levels 1. Each energy level can hold a specific number of electrons and cannot accommodate more than that. Any excess electrons will occupy the next energy level. 2. Lower energy levels are filled with electrons first, followed by higher energy levels. For example, the first level (K) is filled first, then the second level (L), then the third level (M), and so on, depending on the number of electrons in each atom. 3. The outermost energy level of any atom cannot hold more than 8 electrons, regardless of its number, except for the K level, which can hold no more than 2 electrons. Calculating the Number of Electrons in the Principal Energy Level: The number of electrons needed to fill the first four energy levels can be determined using the formula 2n2 where n represents the number of the main energy level. For example: K n=1 = 2(12) = 2 electrons L n=2 = 2(22) = 8 electrons M n=3 = 2(32) =18 electrons N n=4 = 2(42) = 32 electrons Electronic configuration of some elements: 10 Isotopes Isotopes are different forms of the same element. - They have the same number of protons (atomic number) but different numbers of neutrons, leading to differences in atomic mass. Examples: Hydrogen has three main isotopes: These isotopes differ in atomic mass because they have different numbers of neutrons, but they all have the same number of protons. 11 G.R: isotopes of an element differ in their atomic mass. Due to difference in the number of neutrons in the nuclei of isotopes. 12  Lesson (2): The periodic table of elements Scientists made several attempts to classify elements to facilitate their study & find relations between them and their physical and chemical properties: Mendeleev’s table a) First periodic table for classification of the elements. b) Elements were arranged in ascending order according to their atomic masses without a regular pattern upon moving from left to right in horizontal rows called periods. c) He discovered that their properties are repeated periodically at the beginning of each new row. A profile of the scientist 1-He was a Russian chemist who published his periodic table of elements in 1869 and later he modified it. 2- He was honored 48 years after his death by naming one of the discovered elements after him which is Mendelevium (Md) Mosley’s table a) After Rutherford discovered the protons, Mosely discovered that the periodicity of elements properties is related to their atomic number rather than their atomic masses. b) He modified Mendeleev’s table by arranging the elements in an ascending order according to their atomic number. c) So that atomic number of each elements exceeds the atomic number of the preceding element in the same period by (1) d) He also added the noble (inert) gases & other new elements discovered after Mendeleev formulated his table 13  The modern periodic table a) Some inadequacies in Mendeleev’s table prompted the scientist to try to modify it. b) The elements were rearranged in a regular ascending order according to their 1- atomic numbers 2- the way to fill the energy sublevels with electrons in the modern periodic table. It contains 118 elements 7 Horizontal periods (each starting with a new energy level) 18 Vertical groups (each has a traditional number and a modern number) 2 elements 8 elements 8 elements 18 elements The basis for classifying elements Mendeleev's Moseley's The Modern periodic table periodiv table periodic table -Their atomic numbers. Their atomic masses Their atomic numbers - The method of filling the energy sublevels with electrons 14  Elements of the periodic table are classified according to the physical state into: Solid Elements Liquid Elements Gaseous Elements Most of the elements of the periodic table Two elements 11 Elements 5 Nonmetal gases which are: 1- Hydrogen (H) 1- Lithium (Li) 1- Mercury (Hg) 2- Bromine (Br) 2- Nitrogen (N) 2- Sodium (Na) ‘ The only liquid ‘ The only liquid 3- Oxygen (O) 3- Carbon (C) Metal’ nonmetal’ 4- Fluorine (F) 4- Phosphorous (P) 5- Chlorine (Cl) 5- Iron (Fe) 6 Inert gases which are: 1- Helium (He) 2- Neon (Ne) 3- Argon(Ar) 4- Krypton (kr) 5- Xenon (Xe) 6- Radon (Rn) Main blocks of Modern Periodic Table Elements Four main blocks: 1- s-block 2- p-block 3- d- block 4- f-block 15 s-block It is located on the left side of the periodic table. It consists of two groups labeled with letter A, which are: 1A and 2A groups. Group 1A elements Group 2A elements They are all metals except They are all metals. hydrogen element. They are known as alkaline They are known as alkali earth metals. metals. Their electron configurations Their electron configurations end with 2 electron. end with 1 electron. 12Mg 2,8,2 Example: Sodium 11Na 2,8,1 1A 2A 16  p-block It is located on the right side of the periodic table. It consists of 6 groups labeled with the letter A. Except group 0 Penultimate (before the last) group Last group (0) elements (7A) elements They are nobels(Inert) gases. Their electron configurations They are nonmetals. end with 8 electrons. They are known as halogens. Except helium, which ends with Their electron configurations end 2 electrons with 7 electrons. Example: Argon. Example: Chlorine. 18Ar 2,8,8 17Cl 2,8,7 p-block element includes: 3-Some other metals, Example: Aluminum. 13Al 2,8,3 1- All nonmetals whose electron configurations mostly end with 5, 6 or 2- noble gases, 7 electrons. Example: Neon. Example: Phosphorus 15P 10Ne 2,8 4- All metalloids 2,8,5 17 All metalloids, which cannot be identified solely by their electron configurations, due to the difference in the number of electrons in their outermost energy levels, as illustrated in the following table: Boron Silicon Germanium Arsenic Antimony Tellurium Metalloid B Si Ge As Sb Te Number of the period 2 3 4 4 5 5 Number of the group 3A 4A 4A 5A 5A 6A Number of electrons in the outermost 3 4 4 5 5 6 energy level 18  Comparison between some groups in the (S) and (P)-blocks: Points of 1A 2A 7A 0 comparison Group name Alkali metals Alkaline earth Halogens Noble gases metals The block of S S P P the elements Number of 1 electron 2 electrons 7 electrons 8 electrons electrons in except Helium the outer most 2 electrons energy level Example 3Li: 2 , 1 4Be : 2, 2 9F : 2, 7 10Ne :2,8 Type of the All are metals All are metals All are All are noble element except nonmetals gases Hydrogen 19  (d)-block elements It Occupies the middle of the periodic table, where it separates between: s-block elements (the left side of the periodic table) and p-block elements (the right side of the periodic table) Its elements are all metals. They begin to appear in period (4), and they are called Transition metals. (f)-block It is located at the bottom of the periodic table. Its elements are all metals. From the previous, it is clear that: The periodic table reveals the electron configuration of atoms, where: 1-Most metals have an electron configuration that ends with 1,2 or 3 electrons 2-Most nonmetals have an electron configuration that ends with 5,6 or 7 electrons 3-Noble gases have an electron configuration that ends with 8 electrons (except helium) 20 The periodic Table and the Electron Configuration of Elements -Elements 3Li , 11Na , 19K are similar in the number of the electrons in the last energy level (one electron ) Li Na K -Elements 11Na , 12Mg , 13 Al are similar in the number of energy levels occupied by electrons (3 levels ) 21 In the modern periodic table: - Elements of the same group share similar chemical properties G.R Because they have the same number of electrons in the last energy level in each of them. - Elements of the same period are similar in the number of the energy levels occupied by electrons. Both 13Al , 17Cl are located in the same period in the modern periodic table So Both of their atoms have the same number of energy levels (3 energy levels). Lewis Dot structure for Valence Electrons The scientist Lewis proposed a simplified method to represent the number of the electrons which are found in the last energy level around the element symbol , known as Valence electrons , Using dots (.) which are distributed on the four sides of the element symbol , individually (singly) first , and then they are paired up until they are distributed completely. 22 Valence electrons: They are electrons found in the last energy level of the element atom. Lewis Dot structure for Valence Electrons of Sulphur Atom 16 S -Electron configuration of Sulphur atom 16 S : 2,8,6 - The (6) Valence electrons are represented by single dots (.) first on the four sides of the Sulphur symbol, then pairing them until they are distributed completely as follows: It is possible to conclude the valency of an element from the number of the unpaired (single) electrons in its Lewis structure. Number of the unpaired (single) electrons in the Lewis structure = 2 Sulphur is Divalent. 23