Grade 9 Academic Homework Answers

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1 Grade 9 Academic Homework Answers From Particles to Solutions Lesson p. 178 # 1-6, 8, All matter is composed of tiny particles separated by empty spaces. Different substances are made up of different types of particles. Particles are in constant, random motion. Particles of a substance move faster as its temperature increases. Particles attract each other. 2. When particles are heated up, they gain thermal energy. This gained energy breaks the attraction between particles allowing them to slide past one another and form a liquid state. 3. Pure substances include: distilled water, carbon, gold 4. Mixtures include: tea, concrete, and cereal 5. A mechanical mixture is a mixture in which all of the different particles can be distinguished with the unaided eye. Example: Granola Bar 6. A solution is a type of mixture in which the substances combined together cannot be distinguished. Only one phase is visible. Example: tap water 8. a) a pane of clear glass - solution b) chocolate chip ice cream - mechanical mixture c) clear apple juice - solution d) a pizza - mechanical mixture e) garbage in a garbage can - mechanical mixture 10. Lead is no longer used in solder because it is highly toxic and prone to leaching at higher temperatures. Lead can cause irreversible damage to the brain, kidneys, heart, and reproductive organs. Physical and Chemical Properties Lesson p.182 # 1-5; p.186# Qualitative properties are not measured and do not have a numerical value like colour, malleability, hardness, and electrical conductivity. Quantitative properties are measured and include temperature, height, and mass. 2. a) It is red and grey in colour - qualitative b) It is 60 cm long - quantitative c) It is soft and stretchable - qualitative d) It will shrink in 70oC water quantitative 4a. a piece of copper wire- hard, shiny, copper coloured, conductive b. 500g of butter- 500g, yellow, greasy, malleable c. a glass of milk- white, opaque, liquid, viscous d. A candle - malleable, waxy, soft, cylindrical e) A piece of aluminum foil - shiny, conductive, silver coloured, malleable

2 f) A spoonful of sugar - white, crystalline, sweet, soluble in water g) Toothpaste - soft, viscous, white, sticky 1. A chemical change is the change in the starting substance or substances and the production of one or more new substances. No new substances are produced in a physical change. 2. Freezing water is only changing the state of the substance from a liquid to a solid and no new substance is produced. 3. a) metallic lustre - this is a physical property because lustre does not involve creating a new substance. b) boiling point - this is a physical property because it involves a change of state. c) Explodes when ignited - this is a chemical property because a chemical reaction has triggered the explosion and new substances are produced by the explosion d) changes colour when mixed with water - this is a chemical change because a chemical reaction is likely to have created the colour change. 4. a) water boils and turns into steam - physical change b) Wood is sawed and made into a toy box - physical change c) Firewood burns and ashes remain - chemical change: the reaction between the fire and the wood produces new substances, such as carbon dioxide and ash, and the process cannot be reversed. d) Orange drink crystals are stirred into a pitcher of water - physical change e) Sugar, eggs, and flour are mixed and baked into cookies - chemical change: there are colour changes, texture changes, and smells emitted that all point toward a chemical change occurring. 6.a) A physical change I observed was the wax changing state from a solid to a liquid as it was heated. b) The candle became shorter because the wax was being burned. There was a chemical change that turned the wax into new substances, such as gases that escaped into the air. The candle also became shorter because some of the wax near the flame melted and dripped to the base of the candle where it solidified. c) The emission of light and thermal energy, and wax changing into gas, indicates that a chemical change is taking place. Table of Elements Homework pg.215#1, 2, 4-7, 9 1. Tin, chromium, arsenic, and nickel are elements. They can be found on the periodic table. 2. An element is a substance that cannot be broken down into simpler substances. A compound is a pure substance that consists of two or more elements that are chemically joined. 4. The line divides the metallic elements on the left from the non- metallic elements on the right. the elements along this border are the metalloids, which exhibit both metallic and non- metallic characteristics.

3 5. There are more metallic elements than non- metallic. 6. Metals are lustrous, malleable, and good conductors of electricity. 7. Non metals have a low lustre, poor conductors of electricity, and brittle. 9.a) Copper and aluminum can be worked into new shapes and are good conductors of thermal energy. b) Silver and gold can be worked into new shapes and are resistant to corrosion. c) Argon is a poor conductor of thermal energy. Patterns in the Periodic Table Homework pg.225# 1, 2, 4, 5, 8, 9, a) Incorrect. Elements listed in rows on the periodic table are in the same period. b) Incorrect. Elements in the same column have similar physical properties c) Correct d) Correct 2. a) Chlorine is a halogen b) Magnesium is an alkaline earth metal c) Potassium is an alkali metal d) Helium is a nobel gas 4. Sodium is highly reactive and would corrode rapidly. It is also too soft to hold in place with screws. These properties make it unsuitable for use in electrical wires. 5.a) Alkali metals are shiny, silvery, and relatively soft. They also have a relatively low density and react vigorously with water and non metals such as halogens. b) Alkaline Earth metals are shiny and silvery, but have higher densities and are less reactive than the alkali metals. They burn with colourful flames. 8. Alkali metals are so reactive that they combine quickly with other elements in nature, such as halogens. 9. Iodine dissolved in alcohol is used as a disinfectant Chlorine is used to purify water, Iodine and bromine are added to lamps to increase their brightness and operating life. 10. Alkaline earth metals are used in fireworks. Calcium is an important nutrient, helping us to form strong bones and teeth. Magnesium is used in lightweight alloys, such as car wheels. Explaining the Periodic Table pg.240 # No. Number of protons is unique to each element. So different elements always have different numbers of protons. 2. No. Isotopes of the same element have different numbers of neutrons which gives them different atomic masses.

4 3. A. Correct. b. False, atomic mass is larger. c. Usually not equal. Mass number is the rounded atomic mass. d. False. Number of protons is equal to the number of ELECTRONS. E. Correct f. Correct 4. Number of neutrons of nickel is 59-28= First- 2 electrons, second- 8 electrons, third- 8 electrons 6. Ask teacher 7. Bohr rutherfords for: sulfur, argon, potassium, oxygen Putting Atoms Together Homework pg.261 # 1, 2, 3, a. it has 4 different elements b. one sodium, one hydrogen, one carbon, three oxygen c. yes. Sodium is a metal. The rest are non- metals

5 2. neon are elements (only one atom), compounds are all of them, atoms are neon, molecules are all of them. 3. Diatomic molecule is a molecular element. It is when you have only one type of atom bonded to at least one other atom of the same element. Eg. O2 11. a. molecular element b. ionic compound c. ionic compound d. molecular compound How Atoms Combine Homework pg. 266# 1ac, 2, 3a- c, 4f, 6, 7 1a. 58% (14/24) c. 14kt gold is not a pure substance. It has other elements mixed in with it (alloy) 2. Alloy is a mixture of different metals together. They are melted, mixed together, and then allowed to cool back into a solid. 3a. bleach b. ozone c. salt 4f. CH4 6. Bohr- Rutherford for fluorine molecule and hydrogen fluoride 7. Molecules are made of non- metals only and share their electrons. Ionic compounds are made of metals and non- metals and the metal donates an electron to the non- metal