Quarter 2 Reviewer Grade 9 Science (Chemistry) SY 2023-2024 PDF

**REVIEWER FOR SECOND QUARTER EXAMINATION** **Grade 9 -- SCIENCE (CHEMISTRY)** **SY 2023 -- 2024** **Module 1: Electronic Structure of Matter** **Rutherford's nuclear atomic model describes the atom as mostly empty space. Its mass is concentrated in the nucleus that consist of protons and neutro...

**REVIEWER FOR SECOND QUARTER EXAMINATION** **Grade 9 -- SCIENCE (CHEMISTRY)** **SY 2023 -- 2024** **Module 1: Electronic Structure of Matter** **Rutherford's nuclear atomic model describes the atom as mostly empty space. Its mass is concentrated in the nucleus that consist of protons and neutrons. However, it could not explain the chemical properties of elements.** **Bohr's atomic model describes the atom like a solar system, where the electron is found only in specific circular paths, or orbits, around the nucleus. In the Bohr model, each electron carries a fixed amount of energy and does not lose energy as long as it stays in its given orbit. The fixed energies that the electrons are called energy levels. An electron that has received enough energy can jump to a higher energy level. When the electron returns to a lower energy level, energy is emitted in the form of light. The Bohr model was later replaced by a model of the atom that showed that electrons are not limited to fixed orbits around the nucleus. Through mathematical calculations, scientists explained that there is only a probability that the electron can be found in a certain volume in space around the nucleus.** **This volume or region of space around the nucleus where the electron is most likely to be found is called an atomic orbital Schrodinger formulated a mathematical equation that describes the behavior of the electron. The solution to the equation is used to calculate the probability of finding the electron at a particular region in space around the nucleus.** **The quantum mechanical model of the atom describes the atom as having a nucleus at the center around which the electrons move. This model describes a region in space where the electron is most likely to be found.** **An electron is imagined to be a cloud of negative charge having a certain geometrical shape. The electrons are arranged in principal or main energy levels that consist of one or more sublevels. The way in which electrons are distributed in the different orbitals around the nucleus of an atom is called the electron configuration. Filling of electrons start from lower energy level to highest energy level.** **Module 2: Types of Compounds Based on their Properties (Ionic and Covalent)** **Covalent compounds are chemical compounds in which a bunch of atoms are all bonded together with one another via covalent bonds. Covalent bonds, as you may or may not know, occur when two atoms share two electrons. If you have a single covalent bond between two atoms, there are two shared electrons, while a double covalent bond results in four shared electrons.** **Ionic compounds are very different from molecular compounds. This is primarily because they are held together by very different bonds. First and foremost, ionic compounds consist of ions that are held together by electrostatic forces as a result of the transfer of electrons; whereas, molecular compounds do not contain ions, but neutral atoms that held together by a sharing of electrons.** **When ionic compounds are dissolved in an aqueous solution, ions carry the charges throughout the water, allowing ionic compounds to conduct electricity in water. On the contrary, since there are no ions in molecular compounds to carry electric charges in an aqueous solution, one might expect the molecular compounds do not conduct electricity in water.** **Hydrocarbons, molecular compounds that contain carbon and hydrogen, are flammable and can undergo combustion. Combustion actually means the release of energy when the compound reacts with oxygen gas to form carbon dioxide and water.** **Nonmetals are types of elements that lack metallic characteristics; they are usually gases at room temperature, they are poor conductors of heat and electricity and they gain electrons to form negative ions.** **Metals have many uses. Without metals, there would be no cars, building, bridges, cookware, coins, and jewelry. Most of the solid metals that you encounter are not pure elements, but alloys. An alloy is an example of metallic compound. When two or more metallic combine, they form a metallic compound.** **Metallic compounds are generally strong and durable. They are malleable and ductile and good conductors of heat and electricity. Their strength indicates that the atoms are difficult to separate, but their malleability and ductility suggest that the atom are relatively flexible easy to move in various directions. The electrical and thermal conductivity suggests that it is easy to move electrons in any direction in these materials.** **Main Properties Metallic Compound** **1. Strong** **2. Ductile** **3. Malleable** **4. Conductive of heat and electricity** **Module 3: Formation of Ions** **Metals have low electronegativity and ionization energy, thus they tend to transfer or loose of electrons. Non-metals have high electronegativity and ionization energy. They have tender tendency to attract electrons towards themselves. This non-metal tend to gain electron.** **Lewis Dot Structure -- Ionic Bond** **Module 4: The Carbon Compound** Carbon atoms have special abilities. Carbon atoms can form chemical bonds with other carbon atoms and other non-metal atoms in many ways. They can form single, double and triple bonds. These abilities of carbon atoms are the reason why there are so many kinds of organic compounds. Organic compounds are compounds that are primarily composed of carbon atoms, which are chemically bonded with hydrogen and other elements such as oxygen, sulfur and nitrogen. Organic compounds are naturally produced by living organisms, but can also be produced artificially. Organic compounds such as gasoline, kerosene, ethyl alcohol, isopropyl alcohol, formaldehyde, acetic acid, acetone and lubricating oil have important uses. These uses are based on their specific chemical properties. Hydrocarbons are a specific group of organic compounds which contain carbon and hydrogen atoms only. The three basic groups of hydrocarbons are alkanes, alkenes and alkynes. Alkanes have single bonds between carbon atoms. Alkenes have double bonds between carbon atoms. Alkynes have triple bonds between carbon atoms. Ethyne or commonly known as acetylene is an alkyne hydrocarbon with a chemical formula C2 H2. This compound is being used as fuel in oxy-acetylene welding torch. Ethyne (acetylene) is also produced when Calcium Carbide, CaC2 , reacts with water in the air. It can speed up the ripening of fruits. That is why fruit vendors used calcium carbide in ripening their fruits in just few days. Ethene is a gaseous organic compound with a chemical formula CH2 CH2. It is responsible for the ripening of fruits in plants. Alcohols are a group of organic compounds that contains a hydroxyl group,-OH, that is chemically bonded to a carbon atom in the compound. They have special uses such as disinfectant, fuel and as a main component (ethyl alcohol) of liquor and other alcoholic drinks. **Module 5 -- Mole** MOLE - is defined as the quantity of a substance which contains the same number particles as 12.000g of carbon-12. The particles may be atoms, molecules, or ions. 1 mole = 6.02x1023 \- is called Avogadro's number (represented by the symbol N) \- named after Italian chemist and physicist Amadeo Avogadro \- is the number of particles in one mole of a substance. This is a very large number equal to 602 000 000 000 000 000 000 000 **Molar Mass** - the mass in grams of a mole of a substance. Its unit of measurement is g/mol. **Molecular Mass** - is the sum of the molar masses of the elements in the compound for covalent compound. **1.** Which of the elements below has a stable electron configuration? A. sodium C. argon B. chromium D. nitrogen **2.** The numbers of protons, neutrons, and electrons in a zinc atom are: A. 30, 35, 30 C. 30, 65, 35 B. 30, 65, 35 D. 65, 35, 30 **3.** An aluminum atom has the following number of neutrons: A. 27 C. 13 B. 40 D. 14 **4.** Which sublevel does the last or differentiating electron of boron, occupy? A. s C. d B. p D. f **5.** The number of valence electrons in an atom of chlorine is A. 7 C. 4 B. 3 D. 10 **6.** What is the Lewis symbol for phosphorus? A. **P** C. **P** B. **P** D. **P** **7.** Which of the following statements best describes why covalent compounds do not carry electricity when dissolved in water? *For number 24, refer to the images below,*  **8.** The pictures above are examples of: A. Organic Compounds C. Condiments B. Inorganic Compounds D. Liquid **9.** Which are TRUE about organic compounds? I. Organic compounds contain calcium. II\. Organic compounds contain carbon. III\. Organic compounds can be produced by living organisms. IV\. Organic compounds can be produced artificially. A. I, II and III only C. II and III only B. I and III only D. II, III and IV only **10.** Which is the right name for this hydrocarbon? H H H H H C C C C H H H H H A. propane C. pentane B. butane D. hexane **11.** What are the main properties of alkenes that distinguish them from other hydrocarbons? A. hydrogen and carbon components C. naming of alkenes B. presence of double bonds D. uses of alkenes 12\. One of the Greek philosophers who argued that matter is made up of \"uncuttable\" particles called atomos, A. Empedocles C. Archimedes B. Aristotle D. Democritus 13\. An element\'s atomic number specifies how many A. electrons in the nucleus C. The nucleus contains protons. B. Neutrons in the nucleus D. neutrons and the amount of protons in the nucleus 14.The f sublevel has the largest number of electrons. A. 14 C. 6 B. 10 D. 2 15\. Calcium, copper, and cobalt each have their own chemical symbols: A. Ca, Co, and Cu C. C, Ca, and Cu B. Ca, Cu, and Co D. C, Co and Cu **16.** Cooking gas or liquefied petroleum gas ( LPG ) is a mixture of **C~3~H~8~** and **C~4~H~10~**. Which are these compounds? A. pentane and butane C. propane and methane B. methane and butane **D. propane and butane** 17\. The molar masses of the components of a compound are added together to determine its molecular mass. When exactly do we use the word molecular mass? A. For a covalent compound C. for metals B. For the ionic compound D. For all compounds 18\. Phosphoric acid (H3PO4) is a component of detergents, fertilizers, toothpaste, and carbonated beverages. How much P is there in this compound by mass? A.32.0% C. 31.0% B.31.6% D. 30.0% 19\. The chemical formula of washing soda, or sodium carbonate, is Na2CO3. What is its formula mass? A. 51 g/mol. C. 106 g / mol B. 52 g/mol D. 96 g / mol For numbers 45 to 46, consider the following: a silicon chip in a computer\'s integrated circuit weighs 6.2 g. 20\. The chip has moles of silicon. A. 0.22 mol C. 87 mol B. 0.44 mol D. 170 mol 21\. The chip\'s silicon atom count is A. 3.6 X 10 -25 atoms in C. 1.3 x 10-25 atoms B. 7.3 x 10 -25 atoms D. 2.6 x 10-25 atoms 22\. Consider acetone ((CH3)2CO), a typical organic solvent. Acetone has the following molecular mass: A. 32 g/mol at C. 50 g / mol B. 46 g/mol D. 58 g / mol23. In a laboratory experiment, 2 moles of a chemical are broken down into its basic elements. The molar mass of the chemical is discovered to be 80 g/mol. What can be deduced about the compound\'s composition based on the individual molar masses of 40 g/mol and 20 g/mol? A. The compound consists of two distinct components. B. The compound has twice as many moles as either of the elements. C. The compound\'s molar mass is the sum of its constituent elements\' molar masses. D. The compound contains half the number of particles as either element. 24\. In a chemical reaction, 2 moles of material A combine with 3 moles of substance B to yield 1 mole of product C. What can be concluded about the relationship between the number of moles, mass, and number of particles in this reaction if the molar masses of A, B, and C are 20 g/mol, 30 g/mol, and 40 g/mol, respectively? A. C has less mass than A and B combined. B. The number of moles in B is less than in A. C. The molecular mass of A is larger than that of C. D. The reactants have the same number of particles as the result. 25\. What unit of measurement is used to express the amount or quantity of a substance? A. amu B. m3 C. mg D. mol 26\. Water has a molecular mass of 18 grams per mol. How many moles of water are there in 6 grams of water (H2O)? A. 0.52 mol C. 0.33 mol B. 1.80 mol D. 0.48 mol 27\. Al2(S2O3)3 contains the following number of sulfur atoms: A. two C. five B. three D. Six 28\. Avogadro\'s number of particles equals one mole. A. 6.02 X 10 -23 C. 6.20 X 10 -23 B. 6.02 X 10 23 D. 6.20 X 10 23 29\. Which of the following scenarios best illustrates the use of the mole concept to determine the mass of a substance? A. A student calculates the number of moles of water molecules in a sample. B. A chemist determines the volume of a gas under normal temperature and pressure. C. An experimenter determines a liquid\'s density by dividing its mass by its volume. D. A mass spectrometer is used by researchers to determine the atomic composition of a chemical. 30\. Which of the following pairings of organic compounds is extremely flammable? A. Gasoline, acetone C. lubricating oil and isopropyl alcohol B. Water, ethyl alcohol D. liquefied petroleum gas and kerosene 31\. Mang Lowel, a fisherman, returned home with some of his catch and instructed his son to boil the fish. But his son remarked, \"Father, the stove has already run out of fuel\". Then his father instructed him to purchase some so that they could begin frying the fish. Which organic chemical do you believe the boy will purchase? A. kerosene C. Lubricant oil B. gasoline D. isopropyl alcohol 32\. Christian is applying something to the ball bearings on his bicycle\'s wheels to reduce friction. Which of the following materials do you believe he\'s using? A. Vinegar C. kerosene B. Isopropyl alcohol D. Lubricant oil 33\. Which of the following is not a characteristic of carbonyl compounds? A. Disinfectant C. protecting organic compounds B. Cleaning agent D. Embalming human cadavers 34\. What is the most harmful byproduct of hydrocarbon combustion if there is insufficient oxygen? A. carbon C. Carbon Monoxide B. Carbon dioxide D. water 35\. Consider the following organic compounds: acetone, ethanol, and ethanoic acid. Which molecule is most likely to be employed as a solvent in the pharmaceutical sector due to its chemical properties? A. Ethanol C. Ethanoic acid B. Acetone D. None of the aforementioned.36. Which of the following statements best illustrates the use of carbon\'s capacity to generate isomers? A. Carbon can create double bonds with additional carbon atoms, resulting in unsaturated hydrocarbons. B. Carbon atoms may combine with hydrogen and oxygen to form a vast range of organic molecules. C. Isomers are chemical molecules that share the same functional groups but differ in connectivity or spatial organization. D. Carbon\'s electronegativity enables it to create polar covalent bonds with other substances. 37\. Which hydrocarbon molecule has a double bond within its atom? A. Ethane C. propene B. Methane D. propyne 38\. When calcium carbide is dropped in water, what gas is created that can be utilized to melt metal? A. Carbon monoxide C. acetylene B. carbon dioxide D. methane 39\. Maria is a student assistant in their school\'s chemistry lab. Which of the following demonstrates a direct application of compound property knowledge as a student helper in a Chemistry laboratory? I. In the correct storage of various compounds for safety. II\. Assisting pupils with proper substance use. III\. Reading chemical labels might help you recognize harmful compounds. IV\. Keeping track of borrowed laboratory gear and equipment in the lab. A. I only had C. Just I and II B. II (only) D. Only III and IV. 40\. When oxygen is combined with magnesium, it tends to A. loses six electrons C. sharing two electrons. B. accepts two electrons D. share six electrons 41\. Which of the following is true regarding ionic compounds? A. Have low melting and boiling points in Celsius. C. Do not conduct electricity. B. generated via electron sharing D. Soluble in water 42\. What do you call the ion with a positive charge in its atom? A. Anions C. Polyatomic ions. B. Cations D. Polymer Ion 43\. Cooking pans and pots are made of copper and aluminum, which are A. Excellent conductors of electricity. C. shiny B. malleable D. excellent conductors of heat44. The number of electron pairs shared between carbon and oxygen in a carbon dioxide (CO2) molecule is A. one C. three B. two D. four 45\. When fluorine and oxygen interact, they tend to A. Accept electrons. C. contribute electrons B. Share electrons in D. contribute protons. 46\. Metals can be formed into tiny wires. This characteristic is known as A. Ductility C. conductivity B. Malleability D. elasticity 47\. When nonmetals form anions, they A. Lose electrons at C. Gain protons. B. Gain electrons D. Lose protons. 48\. Classify the type of bond made in the Silver Bracelet. A. ionic bond C. A nonpolar covalent link. B. Polar covalent bond D. Metallic bond 49\. The electronegativity increases with the atomic number of the atoms in period 3. A. Temperatures often rise C. Increases then drops B. Generally reduces D. declines and increases 50\. An atom of chlorine has the following primary energy levels: A.7 C. 4 B.3 D. 10