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Goal • Use this page to review the concepts in Unit 2, Chemical Reactions and Radioactivity.
Chapter 4 Atomic theory explains the formation of compounds. Atoms are neutral. In ions, the number of electrons and protons differ, giving the ion an electrical charge. (4.1)
Compounds containing a metal and a non-metal usually form ionic compounds in which positive and negative ions are connected by ionic bonds. Compounds containing only non-metals form molecules in which the atoms are connected by covalent bonds. (4.2)
Chemical equations are words or symbols that identify the reactants and products in a chemical reaction. (4.3)
The law of conservation of mass states that the total mass of all the reactants in a chemical reaction is equal to the total mass of all the products. (4.3)
Chapter 5 Compounds are classified in different ways. The formula of an acid has an H on the left side. The formula of a base has an OH on the right of a metal. A salt is an ionic compound formed from an acid-base neutralization. (5.1)
The pH scale is a way of measuring the concentration of the H+ ion. A neutral solution has a pH = 7, an acidic solution has a pH < 7, and a basic solution has a pH > 7. (5.2)
Oxides that contain a metal react with water to form basic solutions. Oxides that contain only non-metals react with water to form acidic solutions. (5.2)
Organic compounds are compounds that contain carbon and usually contain hydrogen. (5.3)
Chapter 6 Chemical reactions occur in predictable ways. Chemical reactions can be classified as synthesis, decomposition, single replacement, double replacement, neutralization (acid-base), or combustion. (6.1)
It is possible to predict the identity of the products of a reaction based on its classification and knowledge of the reactants. (6.1)
Factors that affect the rate of a reaction include temperature, concentration, surface area, and the presence of a catalyst. (6.2)
A catalyst is a substance that speeds up the rate of a chemical reaction but is still present in its original amounts at the end of the reaction. (6.2)
Chapter 7 The atomic theory explains radioactivity. Isotopes are atoms of the same element that differ in the number of neutrons that they possess. (7.1)
Radioactive decay results from changes in the nucleus of an atom and can produce alpha, beta, and gamma radiation. (7.1)
A half-life is the length of time required for half the nuclei in a sample of a radioactive isotope to decay into its products. (7.2)
Nuclear reactions involve the splitting of heavy nuclei (fission) or the joining together of lightweight nuclei (fusion), both of which can release large amounts of energy. (7.3)
Radioactive decay, fission, and fusion reactions are symbolized using nuclear equations. (7.3)
2. Your teacher has given you an MSDS for another chemical that is commonly used in high school laboratories. Refer to this MSDS to answer the following questions. (a) According to the MSDS, what is the name and chemical formula of the substance?
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Goal • Review features of a simplified modern model of the atom.
A fuzzy, cloudlike region surrounds the nucleus. Electrons exist in this region at certain allowed energy levels. • An atom consists of a tiny, dense nucleus that is surrounded by electrons. • The nucleus contains protons and neutrons. (An exception is the hydrogen-1 nucleus, which
contains one proton only.) Protons and neutrons are also called nucleons. • The nucleus accounts for most of the mass of the atom. • Electrons exist at certain allowed energy levels. Electrons occupy the volume that accounts
for most of the volume of the atom. • Protons carry a positive charge. Electrons carry a negative charge. Neutrons carry no charge.
A neutral atom always has equal numbers of electrons and protons.
Properties of Protons, Neutrons, and Electrons
Subatomic Particle Relative Charge Symbol Mass (g) Relative
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Goal • Demonstrate your understanding of the periodic table.
What to Do
Use your periodic table to answer the following questions. 1. Identify each element.
(a) The element in group 5 and period 5 ____________________________________________ (b) Only halogen that is a liquid at room temperature and pressure ______________________ (c) Alkali metal with the most massive atoms _________________________________________ (d) Synthetic element in period 5 ___________________________________________________ (e) Metal in group 16 and period 4 _________________________________________________ (f) Alkaline earth element with the least massive atoms ________________________________ (g) Noble gas that has atoms with 54 protons _________________________________________
2. Complete the following table. The first row is completed as an example.
Name of Element Atomic Number Number of Protons Number of Electrons
silicon 14 14 14
8
chromium
sodium
13
19 3. Shade in the following chemical families, as indicated, on the outline of the periodic table.
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Goal • Learn an alternative method for writing formulas.
What to Do
The crossover method is a shortcut that can help you determine the formula of an ionic compound. To use the crossover method, follow the steps below. 1. Write the formulas of the ions beside each other. 2. Cross over the magnitude (amount or size) of the charge on the cation (positive ion) so that it
is the subscript for the anion (negative ion). 3. Cross over the magnitude of the charge on the anion so that it is the subscript for the cation. 4. Reduce to lowest terms if necessary. 5. Check your formula.
Model Problem 1
Determine the formula of each compound. (a) magnesium chloride (b) calcium oxide
Solution
(a) Determine the subscripts by crossing over the magnitudes of the charges. Remember that you do not write the number 1.
magnesium chloride
Check the formula by adding the charges on the ions: +2 + [2 × (–1)] = 0 The total charge is zero. The formula is correct. (b)
Because a formula shows the ratio of ions, you must write the simplest ratio. For calcium oxide, the simplest ratio of ions is 1:1.
CaO calcium oxide
Check the formula by adding the charges on the ions: +2 + (–2) = 0 The total charge is zero. The formula is correct.
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Goal • Use this page to review the concepts of the atomic theory and bonding.
What to Do
Circle the letter of the best answer. 1. Which statement is true of elements in the same period in the periodic table?
A. They share similar properties. B. They have the same atomic mass. C. They cannot react with each other. D. They have the same number of energy levels.
2. Which Lewis diagram correctly represents a nitrogen atom?
A.
B.
C.
D.
3. How many protons does an atom of silver contain? A. 47 B. 108 C. 61 D. 60
4. What does a Lewis diagram show?
A. unpaired electrons only B. valence electrons only C. electrons from the innermost energy level only D. all the electrons in an atom
5. An atom is found to have seven valence electrons. To which family of elements in the
periodic table does this atom belong? A. noble gases B. halogens C. alkaline earth metals D. alkali metals
6. What is the nucleus of any atom, except hydrogen, made up of?
A. only neutrons B. only protons C. equal numbers of electrons and protons D. neutrons and protons
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Goal • Use this page to review your understanding of atoms, ions, and compounds.
Circle the letter of the best answer. 1. Which statement best fits the currently accepted model of the atom?
A. Electrons associated with specific energy levels surround the nucleus of an atom. B. An atom is a sphere of positive charge in which electrons are embedded. C. An atom is a small indivisible sphere. D. An atom has a nucleus surrounded by positively charged particles.
2. When metal atoms form ions in compounds, they tend to
A. gain electrons and form positive ions B. lose electrons and form positive ions C. gain electrons and form negative ions D. lose electrons and form negative ions
3. An Al3+ ion contains A. 13 electrons and 13 protons B. 10 electrons and 10 protons C. 10 electrons and 13 protons D. 13 electrons and 10 protons
4. What does the diagram on the right represent?
A. a nickel ion B. a silicon atom C. a nickel atom D. an oxygen ion
5. If you were asked to draw electron Bohr diagrams for the following elements, which element would have a different number of occupied energy levels? A. Mg
2+
B. F–
C. Ne D. Cl–
6. Which list includes only substances with no ionic bonds? A. N2O4, HBr, LiCN B. CO2, NH3, N2 C. SO3, BaCl2, O2 D. NaCl, CH4, Al(OH)3
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Use the following diagram to answer the next three questions.
7. Which unknown represents an element in the halogen family?
A. A B. B C. C D. D E. E
8. Which unknown represents an element that can be classified as a metalloid, having properties of both metals and non-metals? A. A B. B C. C D. D E. E
9. An experiment shows that an unknown element does not easily lose or gain electrons.
Which unknown represents this element? A. B B. C C. D D. E E. E
10. The reaction of solid copper(II) oxide with hydrogen gas at high temperatures produces
copper metal and water. Which chemical equation represents this reaction? A. CuO2 + 2 H2 → Cu + 2 H2O B. Cu2O2 + 2 H2 → 2 Cu + 2 H2O C. CuO + H2 → Cu + H2O D. Cu2O + 2 H → 2 Cu + H2O
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Goal • Check your understanding of Chapter 4.
What to Do
Circle the letter of the best answer. 1. Which subatomic particle(s) make up most of the mass of an atom?
A. electrons B. neutrons C. electrons and protons D. neutrons and protons
2. Which statement best describes the diagram to the right?
A. This is a Bohr diagram that shows eight neutrons. B. This is a Lewis diagram that shows eight neutrons. C. This is a Bohr diagram that shows ten neutrons. D. This is a Lewis diagram that shows ten neutrons.
3. Which statement best describes the following diagram?
A. The pure substance is an element, and the line refers to a charge of 1–. B. The pure substance is a compound, and the line refers to a charge of 1–. C. The pure substance is an element, and the line refers to a pair of bonding electrons. D. The pure substance is a compound, and the line refers to a pair of bonding electrons.
4. What is the name of PbO2?
A. lead(II) dioxide B. lead(IV) oxide C. lead dioxide D. phosphorus boron oxide
5. What is the correct formula for aluminum hydroxide? A. Al3OH B. AlOH3 C. Al(OH)3 D. Al(OH3)
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6. Which statement best describes (NH4)2Cr2O7? A. It is an ionic compound with 16 atoms in total. B. It is an ionic compound with 19 atoms in total. C. It is a covalent compound with 16 atoms in total. D. It is a covalent compound with 19 atoms in total.
7. What is the charge on the plutonium atom (Pu) in the compound Pu2O5?
A. 3+ B. 4+ C. 5+ D. 6+
8. What are the coefficients, from left to right, that correctly balance the following equation?
A. 1, 3, 2, 3 B. 1, 7, 2, 3 C. 2, 7, 4, 6 D. 2, 3, 4, 6
9. What are the coefficients, from left to right, that correctly balance the following equation?
A. 3, 4, 12, 1 B. 3, 3, 6, 1 C. 6, 3, 4, 2 D. 6, 4, 2, 12
10. Which statement best describes the following equations?
I.
II.
A. I is a word equation, and II is a skeleton equation. B. I is a skeleton equation, and II is a balanced equation. C. I is a balanced equation, and II is a word equation. D. I is a skeleton equation, and II is a word equation.
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Goal • In a group assignment, investigate chemical reactions that affect our daily lives.
What to Do
1. Your group will be assigned one topic from the following list. 2. You will be given a total of three class periods to research, prepare information, and present
the topic to your class. 3. During this time, your group is to prepare the following.
(a) A one- to two-page, word-processed report on the assigned topic. This report will be photocopied and handed out to your classmates. Labelled diagrams can be included.
(b) A colourful poster that will be displayed in the classroom. (c) A presentation to the class. This will occur in the third period allotted to this
assignment. Use of originality, video cameras, computer graphics, and so on is encouraged.
Topics
What are the acid-base chemical reactions involved in the following?
1. Film processing 2. Food processing 3. Fabric dyeing 4. Hair dyeing 5. Agriculture 6. Wine-making 7. The pulp and paper industry 8. Mineral processing
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Goal • Demonstrate your understanding of acids and bases.
What to Do
1. Use the following terms and symbols to complete the sentences below. Some terms and symbols will be used more than once, and some not at all.
H+ OH– conduct lower sour bitter NH4
+ sweet red blue greater than less than turns pink remains colourless orange higher do not conduct
(a) Acids are substances that dissolve in water to release __________________ ions. Acids are characterized by a pH value __________________ 7. The __________________ the pH value, the more acidic a solution is. When an acid is added, __________________ litmus turns a __________________ colour and phenolphthalein __________________. Acidic solutions __________________ electricity. Acids are responsible for the __________________ taste in foods.
(b) Bases are substances that dissolve in water to release __________________ ions. Bases are characterized by a pH value __________________ 7. The __________________ the pH value, the more basic a solution is. When a base is added, __________________ litmus turns a __________________ colour and phenolphthalein __________________. Basic solutions __________________ electricity. Bases are responsible for the __________________ taste in foods.
2. Complete the following table about acids and bases. The first row has been completed as an
example.
Name of Substance Chemical Formula of Aqueous Solution Name of Acid or Base
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Goal • Demonstrate your understanding of the concepts, procedures, and safety precautions for using acids and bases.
What to Do
1. Explain why each item is necessary for an activity that involves acids and bases. Show your knowledge of the properties of acids and bases in your answers. (a) Safety glasses
____________________________________________________________________________ 2. What property of baking soda makes it useful for cleaning up acid spills and base spills?
_______________________________________________________________________________ 3. A student has spilled some acid onto his hand. Another student suggests the first student
should apply a basic solution containing hydroxide ions to neutralize the hydrogen ions. (a) Explain why it is not a good idea to attempt to neutralize the acid on the student’s hand.
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Goal • Demonstrate your understanding of salts and metal and non-metal oxides.
What to Do
1. Salts are a class of compounds that include ionic compounds. Salts can be produced when an acid and a base react. Complete and balance the following neutralization reactions. Then, write the name of the salt produced in each reaction.
(a) HBr + NaOH → Name of salt: ______________________ (b) H2SO4 + Mg(OH)2 → Name of salt: ______________________ (c) H3PO4 + Sr(OH)2 → Name of salt: ______________________ (d) HNO3 + Al(OH)3 → Name of salt: ______________________ (e) CH3COOH + Ca(OH)2 → Name of salt: ______________________
2. Metals can react with acids to produce a salt as well as hydrogen gas. Complete and balance
the following reactions of a metal with an acid. In each case, hydrogen gas and a salt will be produced. Write the name of the salt produced in each reaction.
(a) HF + Mg → Name of salt: ______________________ (b) HClO3 + Al → Name of salt: ______________________ (c) H3PO3 + Cu → Name of salt: ______________________ (d) HNO3 + Ca → Name of salt: ______________________ (e) CH3COOH + Zn → Name of salt: ______________________
3. Metal oxides react with water to make solutions that are basic. Non-metal oxides react with
water to produce solutions that are acidic. For each oxide, predict whether dissolving it in water will make the solution acidic or basic.
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Goal • Use this page to practise classifying substances.
What to Do
Complete the following charts. 1. A group of students is given four containers, labelled A, B, C, and D. The students assemble
the following list of characteristics for the four unknown substances. The students know that one of the substances is an acid, one is a base, one is covalent, and one is ionic. Classify each substance.
Substance State at Room Temperature Litmus Paper Test Conductivity Test Classification
A Liquid Red turns blue Conducts
B Solid No change when B dissolved in water
Conducts when dissolved in water
C Liquid No change Does not conduct
D Gas Blue turns red when D bubbled through water
Conducts when bubbled through water
2. The students are told that the substances are methanol, hydrogen sulphide, aqueous
ammonium sulphide solution, and aqueous sodium hydroxide solution. In the following table, write the chemical formula for each substance and the letter that corresponds to the substance.
Substance Chemical Formula Substance Letter (A, B, C, or D)
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Goal • Use this page to review your understanding of acids, bases, and salts.
What to Do
Circle the letter of the best answer. 1. What are substances with a pH above 7 considered to be?
A. basic B. acidic C. salty D. neutral
2. Which is not a characteristic of acids? A. bitter taste B. turn litmus red C. react with bases to form salts D. react with active metals to form H2 gas
3. Four compounds are dissolved in water. Which of the resulting solutions (A to D) are good conductors of electricity? I H2CO3
II NH4OH
III CH3OH
IV NaCl
A. I, II, and III only B. I and III only C. II and IV only D. I, III, and IV only
4. Which of the following is a property of a base?
A. It has a sour taste. B. It turns litmus paper red. C. It tastes bitter. D. It has a pH less than 7.
5. Solution A has a pH of 4, and Solution B has a pH of 6. How many times more acidic is
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Goal • Gain an understanding of the chemistry-related careers.
What to Do
From the list below, select one of the careers in chemistry that interests you. Since this is not an exhaustive list, after some research, you might select another career choice that interests you. Obtain your teacher’s permission first if you wish to report on a different career.
Write a one-page, word-processed report on the career of your choice. Use the following subheadings as a guide for your report.
1. Career Description (nature of the job, type of work done, etc.) 2. Minimum Education Required 3. Salary Expectations 4. Other (for example, career advancement, possible promotions, etc.)
Careers in Chemistry
Analytical chemist Organic chemist Biochemist Pharmaceutical chemist Chemical engineer Pharmacist Chemical engineering technologist Pharmacologist Cosmetic chemist Pharmacy assistant Criminology chemist or technologist Pollution control chemist Dialysis technician or technologist Pollution control technologist Enological chemist Polymer chemist Environmental chemist Quality control chemist Environmental technologist Quality control technician Fingerprint technician Research assistant Food chemist Research chemist Food technologist Science (chemistry) teacher Forensic technician Soil chemist Forestry technologist Soil science technologist Hematology technologist Technical sales Inorganic chemist Technical writer Medical technologist Textile chemist Ophthalmic laboratory technician Toxicologist Optical laboratory technician Water resources technologist
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Goal • Check your understanding of Chapter 5.
What to Do
Circle the letter of the best answer. You may refer to a periodic table, ion chart, pH scale, and pH indicator colour change chart. 1. Which of the following household items is basic?
A. baking soda B. grapes C. bananas D. water
2. What are the colours of methyl red indicator and bromothymol blue indicator in separate
samples of water at pH 7? A. Methyl red indicator is red, and bromothymol blue indicator is yellow. B. Methyl red indicator is yellow, and bromothymol blue indicator is blue. C. Methyl red indicator is yellow, and bromothymol blue indicator is green. D. Methyl red indicator is orange, and bromothymol blue indicator is green.
3. Which are properties characteristic of an acid but not a base?
A. sour, reacts with magnesium, turns litmus blue B. bitter, reacts with magnesium, turns litmus red C. slippery touch, does not react with magnesium, turns litmus blue D. sour, turns phenolphthalein indicator colourless, turns litmus red
4. What the best chemical definition of a salt?
A. a material found by evaporating sea water B. a material formed by the reaction of an acid with a base C. a material containing a metal ion and an oxide ion D. a material containing a metal ion and carbonate ion
5. Burning magnesium in air produces a brilliant white flame and a white powder. When the
white powder is placed in water, it dissolves. What is the colour when bromothymol blue indicator is added to this solution? A. colourless B. yellow C. green D. blue
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6. What is formed when HCl and NaOH solutions are combined? A. NaCl and H2O B. NaH and ClOH C. NaOCl and H2 D. There is no reaction.
7. Which list shows the elements that are the most reactive towards water on the left and least reactive towards water on the right? A. cesium, magnesium, potassium B. cesium, potassium, magnesium C. potassium, cesium, magnesium D. magnesium, potassium, cesium
8. Which of the following compounds are organic?
I Na2CO3
II CH3CH2CH3
III CH3OH
A. I and II only B. II and III only C. I, II, and III D. None of these compounds is organic.
9. Consider the two representations of ethane. What kind of representation is each?
A. The left is a molecular formula, and the right is a structural formula. B. The left is a structural formula, and the right is a molecular formula. C. The left is a ball-and-stick formula, and the right is a space-filling model. D. The left is a space-filling model, and the right is a ball-and-stick model.
10. Which of the following is true of the element carbon?
I Carbon can form four bonds.
II Carbon atoms can combine to form long chains.
A. I only B. II only C. Both statements are true. D. Neither statement is true.
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Match the Term on the left with the best Descriptor on the right. Each Descriptor may be used only once.
Term Descriptor
_____ 11. indigo carmine
_____ 12. inorganic
_____ 13. solvent
_____ 14. acid
_____ 15. concentration
_____ 16. pH scale
A. releases OH- ions in solution
B. compounds that do not contain carbon
C. releases H+ ions in solution
D. acid-base indicator
E. a set of numbers that measure acidity levels
F. a liquid capable of dissolving other substances
G. turns red in acid
H. a measure of the quantity of a substance dissolved in a given volume
Short Answer Questions 17. Name the following compounds and indicate whether each is an acid, a base, or neither.
Compound Name Acid, Base, or Neither?
(a) H2SO4
(b) HCl
(c) Ca(OH)2 18. Complete the following chart.
Indicator Colour at pH 4 Colour at pH 7 Colour at pH 10
Blue litmus paper
Red litmus paper 19. Complete and balance the following equations.
(a) HBr + KOH → KBr + _____ (b) H2SO4 + Al(OH)3 → _____ + ______ (c) The reactions in (a) and (b) are both of the same type. What is the name of this type of
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Goal • Review your understanding of endothermic and exothermic reactions.
What to Do
Read the following summary of exothermic and endothermic reactions. Then, answer the questions on the next page.
Summary
– A chemical change is always accompanied by a change in energy because the atoms or ions that make up the reactants are rearranged.
– During a reaction, chemical bonds that hold the reactant atoms or ions together must be broken and new chemical bonds must be formed within the product substance(s).
– The breaking of chemical bonds requires the input of energy and is defined as an endothermic process.
– The formation of chemical bonds releases energy and is defined as an exothermic process. – Since any chemical change involves both the breaking and formation of chemical bonds,
there are two possible outcomes of any chemical change. – The overall change is exothermic if more energy is released to form the product chemical
bonds than is required to break the reactant chemical bonds. – The overall change is endothermic if less energy is released to form the product chemical
bonds than is required to break the reactant chemical bonds. – The energy that is released or absorbed is related to the external environment of the
chemical reaction. Endothermic reactions absorb thermal energy from the surrounding environment and result in a decrease in temperature. Exothermic reactions, on the other hand, release thermal energy to the surrounding environment and result in an increase in temperature.
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1. Classify each reaction as either endothermic or exothermic, and briefly explain your answer.
Description of Chemical Reaction
Endothermic or Exothermic?
Explanation
A piece of paper is ignited and burns with a bright flame.
Pentaborane (a colourless liquid), B5H9, reacts violently with oxygen gas to form solid diborane, B2O3, and water, typically bursting into flame and often exploding.
Pure iron metal is formed and carbon dioxide is released when iron(III) oxide ore is heated to a very high temperature in the presence of solid carbon.
Sodium hydroxide solution and hydrochloric acid solution are mixed. The temperature of the mixture increases.
Mixing ammonium thiocyanate and barium hydroxide octahydrate in a beaker causes water on the outside of the beaker to freeze.
2. A student claims that the reaction of butane gas and oxygen gas must be endothermic since a
spark is needed to ignite the butane gas in a lighter. Do you agree or disagree with this claim? Explain your answer.
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Goal • Use this page to practise balancing combustion reaction equations.
What to Do
1. Balance each equation for a combustion reaction. (a) C2H6 + O2 → CO2 + H2O
(b) C3H8 + O2 → CO2 + H2O
(c) C6H14 + O2 → CO2 + H2O
(d) C8H18 + O2 → CO2 + H2O
(e) C2H2 + O2 → CO2 + H2O
(f) C2H4 + O2 → CO2 + H2O
(g) C2H6 + O2 → CO2 + H2O
(h) C6H12O6 + O2 → CO2 + H2O
(i) CH4 + O2 → CO2 + H2O
(j) C2H5OH + O2 → CO2 + H2O
2. Write a balanced chemical equation to represent each reaction described below. (a) Candle wax, C25H52, is burned to produce carbon dioxide and water.
(b) Sucrose, C12H22O11, is burned to produce carbon dioxide and water.
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Goal • Use this page to practise classifying and balancing reactions.
What to Do
Classify each reaction as a synthesis (S), decomposition (D), single replacement (SR), double replacement (DR), or combustion (C) reaction. Then, balance each equation.
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Goal • Review your understanding of chemical reactions.
1. Butane gas, C4H10, is mixed with pure oxygen. The mixture is ignited and burns.
(a) Write the balanced chemical equation to represent the reaction.
(b) Explain how the law of conservation of mass is illustrated by the reaction.
2. A solution of calcium hydroxide reacts with sulphuric acid to produce water and calcium sulphate. (a) Write a balanced chemical equation to represent the reaction.
(b) Classify the reaction as a synthesis, decomposition, single replacement, double replacement, or combustion reaction.
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Goal • Check your understanding of Chapter 6.
What to Do
Circle the letter of the best answer. You may refer to a periodic table and an ion chart. 1. What type of reaction is the following?
silver + gold(III) nitrate → silver nitrate + gold A. synthesis B. neutralization C. single replacement D. double replacement
2. What type of reaction is the following?
C3H8 + 5O2 → 3CO2 + 4H2O A. single replacement B. combustion C. decomposition D. double replacement
3. Classify the reaction type and predict the products of the following reaction.
HCl + Mg(OH)2 → ? A. double replacement; products are MgCl and H(OH)2 B. double replacement; products are MgCl2 and H2O C. neutralization; products are MgCl and H(OH)2 D. neutralization; products are MgCl2 and H2O
4. Which of the following reactions is double replacement?
A. Pb + 2CuCl2 → PbCl2 + 2Cu B. Na2CO3 + CaBr2 → CaCO3 + 2NaBr C. MgCO3 + 2HBr → MgBr2 + CO2 + H2O D. Mg(OH)2 + 2HBr → MgBr2 + 2H2O
5. What are the products in the decomposition reaction involving aluminum oxide?
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6. In order to start a campfire, wood is chopped into many small pieces, called kindling. Which factor makes it easier to light a fire using kindling instead of large pieces of wood? A. temperature B. concentration C. surface area D. catalyst
7. When hydrogen gas is mixed with oxygen gas in a closed container, both gases mix but no
noticeable reaction takes place. When a piece of platinum metal is placed in the gas mixture, the mixture suddenly explodes. After the explosion, analysis shows that the amount of platinum metal did not change during the explosion. What factor is responsible for the onset of the explosion? A. The concentration of the oxygen was high. B. The concentration of the hydrogen was high. C. The platinum was a reactant. D. The platinum was a catalyst.
8. The chain on a bicycle rusts faster when the bicycle is left outside in damp conditions.
Which of the following factors affect the rate at which the bicycle chain rusts?
I The surface area of the metal in the chain
II The concentration of oxygen in the air
III The temperature
A. I only B. II and III only C. III only D. I, II, and III
9. A zinc metal strip is placed in hydrochloric acid. Which of the following changes could be
made to decrease the rate of this reaction?
I Add water to dilute the hydrochloric acid.
II Place the beaker on a hot plate in order to raise the temperature.
III Add a catalyst.
IV Change the shape of the magnesium to make it thicker and less wide.
A. I and II only B. II and III only C. I and IV only D. II and IV only
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10. Suppose a chemist performed an experiment by dissolving equal masses of calcium carbonate in separate beakers containing sulphuric acid. The results of three trials are shown in the table below.
Trial Sulphuric Acid Calcium carbonate Temperature
1 Concentrated Finely ground 10oC
2 Concentrated Lump 10oC
3 Dilute Lump 15oC
Trial 1 was the fastest, and Trial 2 was the slowest. Which of the following correctly lists the factors from most important to least important in increasing the rate of this reaction?
A. concentration, surface area, temperature B. temperature, surface area, concentration C. surface area, concentration, temperature D. surface area, temperature, concentration
Match the Term on the left with the best Descriptor on the right. Each Descriptor may be used only once.
Term Descriptor
_____ 11. synthesis
_____ 12. precipitate
_____ 13. combustion
_____ 14. surface area
_____ 15. neutralization
_____ 16. catalyst
A. a reaction in which a compound splits into two elements
B. the reaction involving a burning candle
C. the reaction of an acid with a base
D. a solid that forms when two ionic solutions are mixed
E. a substance that increases reaction rate without being used up by the reaction
F. affects the rate of a reaction between a solid and a liquid
G. a reaction in which two elements combine to form a compound
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Short Answer Questions 17. Identify each of the following descriptions as synthesis, decomposition, single replacement,
double replacement, neutralization, or combustion. (a) There is only one reactant. ___________________________________________________ (b) One reactant is an element. The other is a compound. ____________________________ (c) Two ionic compounds react to form two new ionic compounds. ____________________
18. Which of the four factors affecting reaction rate is most important in each question below?
Choose from among concentration, temperature, surface area, and catalyst. (a) Dust in a granary explodes when it comes in contact with a spark. ______________________ (b) Table sugar is digested in the mouth when it dissolves in saliva, which contains a
digestive enzyme. ___________________________ (c) A person blows on a fire to help get it burning better. _____________________________
19. Complete and balance each of the following equations. Then classify each reaction type.
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2. Complete the following table by filling in the missing information about isotopes. The first row is completed as an example.
Name of Isotope Symbol Mass
Number Number of
Protons Number of Neutrons
hydrogen-3 31 H 3 1 2
scandium-49
Co6027
nitrogen-15
U23892
I12953
56 79
86 48
O188
carbon-14
3. Although oxygen-16 is the most common isotope of oxygen, oxygen-17 and oxygen-18 are
also present. Despite the differences in the atomic structures of the three isotopes, there is no difference in how they form ionic or covalent compounds with atoms of other elements. Explain how this can be.
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Goal • Use this page to show your understanding of isotopes.
Circle the letter of the best answer.
1. What do two isotopes of an element have? A. the same number of electrons but a different number of protons B. the same number of neutrons but a different number of protons C. the same number of protons, electrons, and neutrons D. the same number of protons but a different number of neutrons
2. What does a sodium-23 isotope contain? A. 11 protons and 12 neutrons B. 11 protons and 23 neutrons C. 12 protons and 11 neutrons D. 23 protons and 23 neutrons
3. Isotopes are two atoms of the same element that do which of the following? A. become electrically charged B. differ in mass but are chemically alike C. give away electrons to become positively charged D. have the same mass but different chemical properties
4. Which of the following describes the isotope 4020Ca ?
A. 40 protons and 20 neutrons B. 20 protons and 40 neutrons C. 20 protons and 20 neutrons D. 40 electrons and 20 neutrons
Use the following information to answer the next two questions. The nuclear notations for four mystery elements are shown below.
5626 AA 60
27BB 6028CC 58
28DD
5. How many subatomic particles does mystery element AA have? A. 26 protons, 26 neutrons, and 26 electrons B. 26 protons, 30 neutrons, and 26 electrons C. 30 protons, 26 neutrons, and 30 electrons D. 26 protons, 56 neutrons, and 30 electrons
6. Which mystery elements are isotopes of the same element? A. AA and BB B. BB and CC C. CC and DD D. AA and DD
(b) How long is one half-life for carbon-14? ____________________
(c) What percentage of carbon-14 remains (i) after one half-life? ____________________ (ii) after two half-lives? ________________ (iii) after three half-lives? ________________
(d) Use the graph to estimate the percentage of carbon-14 remaining after
(i) 5000 years __________ (ii) 10 000 years __________ (iii) 15 000 years __________.
(e) Use the graph to estimate the number of years that have passed since the organism died if the percentage of parent isotope that remains is (i) 40% ___________ (ii) 20% ____________ (iii) 5% ____________ .
(f) Explain why carbon-14 half-life measurements are not effective in dating an organism
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2. Volcanic rocks can be dated using the potassium-40 clock, a dating method based on the decay of the potassium-40 isotope into the argon-40 isotope. Potassium-40 can exist as hot molten rock, whereas argon-40, the daughter isotope, escapes from the molten rock because it is a gas. When the molten rock solidifies, potassium-40 is present, but argon-40 is absent. The age of volcanic rock can be measured by comparing the amount of these two isotopes present in the rock.
(a) Why is there no argon-40 present in the molten rock when it solidifies?
(b) After many years, argon-40 is present in volcanic rock containing potassium-40, even though no argon-40 was there to begin with. How did the argon-40 get there?
(c) What is the length, in years, of one half-life of potassium-40? ____________________ (d) Suppose a sample of volcanic rock contained 100 nanograms (a nanogram is a billionth of
a gram) of potassium-40 when the rock first formed. How many nanograms of potassium-40 and of argon-40 would be present in the sample after (i) 1 half-life? ________________
(ii) 2 half-lives? ________________ (iii) 3 half-lives? ________________
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3. The table of parent-daughter isotopes shows three different isotope pairs that are used in radioisotope dating. Examine the chart and answer the following questions.
(a) Lead-207 is called the daughter of uranium-235. What does this mean?
(b) How old is a rock sample that contains uranium-235 and lead-207 in equal amounts? _________________________
(c) The age of Earth was first established in 1953 when Claire C. Patterson of the California
Institute of Technology used a uranium-lead clock to analyze rock. In comparing amounts of uranium-235 with lead-207, he established that slightly less than 8 half-lives of uranium-207 had passed since the rock formed. Using this data, estimate the age of Earth. _________________________
(d) The rocks that make up the Canadian shield are extremely old. They are estimated to be
between 3.7 and 3.8 billion years. (A billion is a thousand million). (i) Estimate how many half-lives of uranium-235 would have passed in a sample of rock
this old. _________________________ (ii) Estimate the percentage of original uranium that would remain in a sample of rock from the Canadian shield. _________________________
(e) Suppose a sample of rock from the Canadian shield were analyzed using the potassium-40
clock. What information could this give about the age of rock?
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Goal • Check your understanding of Chapter 7.
What to Do
Circle the letter of the best answer. You may refer to a periodic table, an ion chart, and a common isotope pairs chart. 1. Which of the following is true of subatomic particles in a nucleus of vanadium-50?
A. It has 23 protons and 27 neutrons. B. It has 23 protons and 28 neutrons. C. It has 27 protons and 23 neutrons. D. It has 27 protons and 51 neutrons.
2. Which of the following nuclear decay equations represent alpha decay?
I 20180Hg→ 201
81T1 + 0-1 β
II 23191Pa → 227
89 Ac + 42He
III 22589 Ac → 221
87Fr + 42α
IV ∗6028 Ni → 60
28 Ni + 00 γ
A. I and IV only B. II and III only C. III and IV only D. I and III only
3. Consider the following partly completed nuclear decay equation.
What is the symbol that correctly completes this equation? A. 14
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4. Refer to the Common Isotope Pairs Chart to determine the maximum effective dating range for carbon-14 dating. A. 14 years B. 5730 years C. 14 600 years D. 50 000 years
5. Refer to the Common Isotope Pairs Chart to determine the age of a sample of rock that
contains equal amounts of uranium-235 and lead-207. A. 355 million years B. 710 million years C. 2.25 billion years D. 4.5 billion years
6. Potassium-40 is a radioactive isotope with a half-life of 1.3 billion years. It has the daughter
isotope argon-40. How old is a rock that is found to contain 1.0 g of potassium-40 and 3.0 g of argon-40? A. 0.65 billion years old B. 1.3 billion years old C. 2.6 billion years old D. 3.9 billion years old
7. Which nuclear symbol correctly completes the following nuclear reaction?
A. 42 He
B. 9237 Sr
C. 9037 Sr
D. 14355 Cs
8. Which equation best represents the type of process that occurs in a CANDU reactor?
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9. Which of the following descriptions apply to the nuclear reactions that produce energy at the core of the Sun?
I Heavy unstable nuclei split apart into two smaller nuclei.
II Lightweight nuclei release energy when they join to form one nucleus.
III The reaction produces products that are radioactive.
A. I only B. II only C. I and III only D. II and III only
10. All of the following are concerns connected with the use of CANDU nuclear reactors. Three of these concerns are considered by nuclear regulators to be of very low risk because technologies and procedures have been implemented to deal with them. Which of these four concerns represents a problem for which no generally accepted solution has been reached? A. The nuclear reactor might have a runaway chain reaction and lead to a meltdown of the
reactor core. B. The nuclear waste produced in the process might be stolen to produce nuclear weapons. C. The nuclear waste lasts millions of years and might leak out into the environment over
time. D. Radioactive isotopes might be emitted during normal operation and harm people
working at the facility and those living nearby.
Match the Term on the left with the best Descriptor on the right. Each Descriptor may be used only once.
Term Descriptor
_____ 11. beta particle
_____ 12. gamma radiation
_____ 13. mass number
_____ 14. daughter isotope
_____ 15. fusion
_____ 16. half-life
A. high energy electromagnetic radiation B. a process involving the joining together of two nuclei C. a process involving the splitting of a large nucleus into smaller fragments D. the sum of the number of protons and neutrons in the nucleus of an atom E. the time it takes for one half of a sample of a radioisotope to decay F. a fast-moving electron that has been ejected from the nucleus of an atom G. a newly formed nucleus produced during a nuclear reaction H. a fast-moving helium nucleus that has been ejected from the nucleus of an atom
__________________________________________________________________________ 18. If 200 micrograms (or 200 billionths of a gram) of carbon-14 were present in a sample of
pollen, how many grams would be left after the following periods? (a) 5730 years _________________________ (b) 14 600 years _______________________ (c) four half-lives _________________________
19. Provide the nuclear symbol for the parent nucleus for each.
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5. How many atoms of each of the following elements are indicated by the formula for ammonium sulphite?
Nitrogen Hydrogen Sulphur Oxygen
A. 1 4 1 3
B. 4 4 3 3
C. 2 6 1 4
D. 2 8 1 4 6. What is the name of the compound PbS2?
A. lead sulphide B. lead disulphide C. lead(II) sulphide D. lead(IV) sulphide
7. Which of the following is an inorganic compound?
A. Na4C B. C2H6 C. C12H22O11 D. CH3COOH
8. What type of reaction would you expect when potassium carbonate reacts with magnesium
nitrate? A. single replacement B. double replacement C. neutralization D. combustion
9. When a flame is brought near a lump of coal, the coal slowly begins to burn. When the
same flame is placed in the path of falling coal dust, an explosion occurs. What is the factor that causes the second reaction to have a faster rate of reaction? A. temperature B. catalyst C. concentration D. surface area
10. What element is formed during the alpha decay of uranium-235?
A. thorium-231 B. neptunium-235 C. plutonium-239 D. protactinium-236
___________________________________________________________________________ 29. Complete each equation by writing the correct nuclear symbol in the blank.
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30. Argon is a gas, and is driven out of molten rock, such as lava. Potassium however, remains in molten rock. Consider the following data for the isotope pairs potassium-40 (parent) and argon-40 (daughter).
Explain how you would determine the age of a rock sample using potassium-40/argon-40 ratios.
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BLM 2-3, Interpreting an MSDS
1. (a) The name of the substance is cupric sulphate pentahydrate. The chemical formula is CuSO4·5H2O. (b) The substance is potentially toxic either by absorption or by inhalation. (c) To avoid exposure, students should wear safety glasses, an apron, and gloves. Although not stated, proper
ventilation is essential. The dust should not be inhaled. (d) Excess amounts of this chemical should be deposited in a labelled waste container. (e) The teacher should be informed immediately. The teacher should immediately contact poison control or
medical personnel to find out how to proceed. It is likely that vomiting will need to be induced. 2. Note: For this question, search the Internet to find MSDS sheets to give your students. Use a search engine to
search for an MSDS for any chemical by typing in “MSDS” and the name of the chemical. You may wish to provide all students with copies of the same MSDS, or provide a variety of MSDS sheets. Answers are given below for an MSDS for strontium nitrate, Sr(NO3)2. (a) The name of the substance is strontium nitrate. The chemical formula is Sr(NO3)2. (b) The substance is slightly dangerous to your health. It may cause irritation of the skin, eyes, lungs, or
gastrointestinal tract. Long-term exposure may result in liver, kidney, bone, blood, and nerve damage. (c) Inhalation of the dust from the chemical should be avoided. Students should wear gloves, goggles, and
aprons. The substance must not be mixed with a reducing agent, because this could cause a fire. (d) In the event of a fire, firefighters should wear full protective clothing and a self-contained breathing
apparatus. (e) All sources of ignition should be removed and proper ventilation should be initiated. Cleaning precautions
should be taken to minimize or avoid dispersion of dust into the air. Waste should be sent to an appropriate hazardous waste facility.
(f) The material should be stored in a cool, dry location. BLM 2-8, Periodic Table Scavenger Hunt
1. (a) niobium, Nb (b) bromine, Br (c) francium, Fr (d) technetium, Tc (e) tellurium, Te (f) beryllium, Be (g) xenon, Xe
1. D 2. C 3. A 4. B 5. B 6. D 7. A 8. D 9. D 10. B 11. D 12. An ionic bond exists between a cation and an anion in an ionic compound. An ionic bond is formed when
electrons are transferred from a metal to a non-metal. A covalent bond exists within a covalent compound. A covalent bond is formed when non-metals share electrons.
BLM 2-20, Atoms, Ions, and Compounds
1. A 2. B 3. C 4. B 5. D 6. B 7. D 8. C 9. D 10. C
hydrogen acetate CH3COOH acetic acid or ethanoic acid
hydrogen sulphite H2SO3 sulphurous acid
BLM 2-26, Working with Acids and Bases
1. The safety glasses, gloves, and lab apron serve the same purpose: to protect against accidental spills and contact with corrosive acids and bases. The eyewash station and safety showers are both used to dilute any acid or base that has contacted living tissues, to the point at which it is not concentrated enough to cause significant damage.
2. Baking soda can act as either an acid or a base. This property means that it can neutralize both acids and bases.
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3. (a) Using a base to neutralize an acid spill to skin tissue is not a good idea because it is difficult to judge the correct amount to use. Too little base and the acid will still be corrosive. Too much base and the corrosive base will damage the tissue. Also, the heat generated by the reaction can further damage skin. (b) The student should immediately dilute the acid on the affected area by flushing with lots of cold water for
several minutes. BLM 2-27, Salts and Metal and Non-Metal Oxides
1. Substance A is a base because it turns red litmus blue and conducts electricity. Substance B is an ionic compound because it conducts electricity when dissolved in water. Substance C is a covalent compound because it is a liquid at room temperature and does not conduct electricity or change the colour of litmus. Substance D is an acid because it turns blue litmus red when dissolved in water and also conducts electricity when dissolved in water.
2. Answers are in boldface.
Substance Chemical Formula Substance Letter (A, B, C, or D)
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A sheet of flexible, colourless plastic is left outside, in bright sunlight, and becomes yellow and brittle over time.
Chemical The change in colour to yellow is a clear giveaway that a chemical reaction took place. The change in the property of flexibility suggests that a new compound was formed.
The light allowed the plastic to react with oxygen to form different compounds.
A teaspoon of white sugar (sucrose) dissolves in a glass of warm water.
Physical The sugar dissolved into the water to form a solution but did not undergo a chemical reaction. No new substances
were formed.
Vinegar is poured over a teaspoon of baking soda. The white baking soda powder fizzes, and bubbles form.
Chemical The fizzing indicates the formation of a gaseous substance, carbon dioxide.
A red-hot nail is inserted into a large block of ice. Steam is formed as the nail contacts the block, and water flows away from the nail.
Physical A state change has occurred, but no new substances are formed.
BLM 2-33, Endothermic and Exothermic
1.
Description of Chemical Reaction Endothermic or Exothermic?
Explanation
A piece of paper is ignited and burns with a bright flame.
Exothermic Heat and light are emitted.
Pentaborane (a colourless liquid), B5H9, reacts violently with oxygen gas to form solid diborane, B2O3, and water, typically bursting into flame and often exploding.
Exothermic Bursting into flames and explosions are both energy emissions.
Pure iron metal is formed and carbon dioxide is released when iron(III) oxide ore is heated to a very high temperature in the presence of solid carbon.
Endothermic High temperatures are required to form the new substances.
Sodium hydroxide solution and hydrochloric acid solution are mixed. The temperature of the mixture increases.
Exothermic Heat is emitted.
Mixing ammonium thiocyanate and barium hydroxide octahydrate in a beaker causes water on the outside of the beaker to freeze.
Endothermic Heat is absorbed from the surroundings.
2. The initial spark is an endothermic requirement, but the overall reaction is exothermic since heat and light are
the end products. Many exothermic reactions (such as combustion reactions) require some initial energy input in order to proceed.
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BLM 2-40, Chemical Reactions Review
1. (a) 2C4H10 + 13O2 → 8CO2 + 10H2O
(b) There are equal numbers of carbon atoms, hydrogen atoms, and oxygen atoms on each side of the equation. Atoms are not transformed, destroyed, or created. Therefore, the mass of the reactants is equal to the mass of the products.
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3. The oxygen isotopes have the same number of electrons and the same number of protons. The number of neutrons does not affect reactivity. How elements form compounds is dictated primarily by the valence electrons.
BLM 2-44, Isotopes
1. D 2. A 3. B 4. C 5. B 6. C BLM 2-46, Half-Life and Radioisotope Dating
1. (a) Half-life is the time needed for half of a sample of a radioisotope to decay. (b) 5730 years (c) (i) 50% (ii) 25% (iii) 12.2% (d) (i) 55% (ii) 30% (iii) 15% (e) (i) 7500 years (ii) 13 000 years (iii) 26 000 years (f) After 50 000 years there is insufficient parent isotope remaining to be able to detect it.
2. (a) Potassium-40 can exist hot molten rock, while argon-40, the daughter isotope, escapes from the molten rock because it is a gas. (b) By radioactive decay of potassium-40 (c) 1.3 billion years (or 1300 million years) (d) (i) 50 nanograms of potassium and 50 nanograms of argon-40
(ii) 25 nanograms of potassium and 75 nanograms of argon-40 (iii) 12.5 nanograms of potassium and 87.5 nanograms of argon-40
3. (a) lead-207 decays into uranium-235 (b) 710 million years (equivalent to one half-life) (c) Estimated age is 5.68 billion years (Claire’s analysis gave 5.55 billion years). (d) (i) About 5 half-lives (ii) 3.125% remains (e) Although the method cannot be used to date rocks older than 3 billion years, the method would still be able
to demonstrate that the rocks were at least that age. (f) Carbon-14 has a half-life in the hundreds of years and there would be no detectable amount present in the
rocks, making carbon-14 dating unable to date the rock. BLM 2-47, Chapter 7 Quiz
1. A 2. B 3. D 4. D 5. B 6. C 7. C 8. B 9. B 10. C 11. F 12. A 13. D 14. G 15. B
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16. E 17. (a) They are made of the same number of protons (19).
(b) They have different numbers of neutrons (20 and 21). (c) Potassium-40 is heavier because the extra neutron that it has increases the mass of the nucleus.
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23.
Name Formula Ionic or Covalent?
lithium iodide LiI ionic
carbon dioxide CO2 covalent
strontium hydroxide Sr(OH)2 ionic 24.
K2S potassium sulphide ionic
CuBr2 copper(II) bromide ionic
SO3 sulphur trioxide covalent 25. (a) C3H8
(b) organic (c) C3H8 + 5O2 → 3CO2 + 4H2O
26.
Reaction Classification
(a) Ni(OH)2 + 2HCl → NiCl2 + 2H2O neutralization
(b) 2Au(CN)3 + 3Zn → 2Au + 3Zn(CN)2 single replacement
(c) O2 + 2Be → 2BeO synthesis
27. (a) Synthesis
(b) 4Na + O2 → 2Na2O (c) There are four atoms of sodium and two atoms of oxygen represented on both sides of the equation,
showing that the reaction is a rearrangement of particles, and that no particles are created or destroyed. This also means the mass does not change, in accordance with the law of conservation of mass.
28. (a) zinc chloride and H2
(b) Any two. For example: raise the temperature, increase the concentration of the HCl, grind the zinc to increase surface area, or add a suitable catalyst.
29. 6028 Ni; 234
90 Th; 2412 Mg
30. It can be assumed that molten rock drives out gases, so that when the lava or magma solidifies, there is no
daughter isotope present. This sets the clock to zero. As time passes, argon begins to be produced as the potassium decays. When the ratio of potassium-40 to argon-40 is 1:1, it means 1.3 billion years have passed since the lava hardened. Different ratios indicate different lengths of time since the rock formed.
