Name: --------------------------------------------------------------Date: --------------------------------------
Grade 9----
Worksheet for Quarter 2
Multiple choice:
1. Dalton’s atomic theory stated that every element was made of atoms that could not be subdivided, atoms
of the same element are alike, and
a. atoms are made of protons, neutrons, and electrons.
b. the nucleus is the center of the atom.
c. atoms can join to form molecules.
d. atoms are constantly in motion.
2. Dalton’s atomic theory was accepted because
a. there was evidence to support it.
b. Democritus said that it was correct.
c. Dalton invented the electron microscope.
d. Dalton showed how molecules are formed.
3. Which statement is true according to Dalton’s theory?
a. Atoms of different elements can join to form larger atoms.
b. Atoms can be subdivided into smaller particles.
c. Atoms of the same element differ in electric charge.
d. Atoms of the same element are exactly alike.
4. Which statement about the atomic nucleus is correct?
a. The nucleus is made of protons and neutrons and has a negative charge.
b. The nucleus is made of protons and neutrons and has a positive charge.
c. The nucleus is made of electrons and has a positive charge.
d. The nucleus is made of electrons and has a negative charge.
5. The charge of an electron is
a. 2.
b. 1. c. 0.
d. +1.
6. Atoms have no electric charge because they
a. have an equal number of charged and noncharged particles.
b. have neutrons in their nuclei.
c. have an equal number of electrons and protons.
d. have an equal number of neutrons and protons.
7. According to Bohr’s model of the atom, electrons behave like
a. planets orbiting the sun.
c. light energy in a vacuum.
b. waves on a vibrating string.
d. planets rotating on their axes.
8. According to Bohr’s theory, an electron’s path around the nucleus defines its
a. electric charge.
c. energy level.
b. atomic mass.
d. speed.
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9. According to modern atomic theory, it is nearly impossible to determine an electron’s exact
a. color.
b. position.
c. charge
d. mass.
10. The order of elements in the periodic table is based on
a. the number of protons in the nucleus. c. the number of neutrons in the nucleus.
b. the electric charge of the nucleus. d. atomic mass.
11. Atoms of elements that are in the same group have the same number of
a. protons.
c. valence electrons.
b. neutrons.
d. protons and neutrons.
12. Valence electrons determine an atom’s
a. mass.
c. electric charge.
b. chemical properties. d. period.
13. Ionization refers to the process of
a. changing from one period to another.
b. losing or gaining protons.
c. turning lithium into fluorine.
d. losing or gaining electrons.
14. A lithium ion is much less reactive than a lithium atom because it
a. is much more massive.
b. has a full outermost energy level.
c. has a negative electric charge.
d. is in a different group in the periodic table.
15. Oxygen’s atomic number is 8. This means that an oxygen atom has
a. eight neutrons in its nucleus.
c. eight protons in its nucleus.
b. a total of eight protons and neutrons.
d. a total of eight neutrons and electrons.
16. An atom’s mass number equals the number of
a. protons plus the number of electrons.
b. protons plus the number of neutrons.
c. protons.
d. neutrons.
17. Which statement about an element’s average atomic mass is correct?
a. It is determined by counting the number of isotopes in a sample of the element.
b. It is equal to one-twelfth the mass of the most common isotope.
c. It is a weighted average, so common isotopes have a greater effect than uncommon ones.
d. It is based on an isotope’s charge, so negatively charged isotopes have a greater effect than
positive ones.
18. An atomic mass unit is equal to
a. one-half the mass of a hydrogen atom.
b. one-fourth the mass of a lithium atom.
c. one-twelfth the mass of a carbon-12 atom.
d. one-fifteenth the mass of a nitrogen-15 atom.
19. Which statement about the alkali metals is correct?
a. They are located in the left-most column of the periodic table.
b. They are extremely nonreactive.
c. They are usually gases.
d. They form negative ions with a 1- charge.
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20. Which of the following elements is an alkali metal?
a. calcium b. magnesium
c. mercury d. sodium
21. Alkali metals are extremely reactive because they
a. have very small atomic masses.
b. are not solids at room temperature.
c. have one valence electron that is easily removed to form a positive ion.
d. have two valence electrons that form compounds with calcium and magnesium.
22. Which statement about noble gases is correct?
a. They form compounds with very bright colors.
b. They exist as single atoms rather than as molecules.
c. They are highly reactive with both metals and nonmetals.
d. They are extremely rare in nature.
23. Semiconductors are elements that
a. have large atomic masses but small atomic numbers.
b. do not form compounds.
c. can conduct heat and electricity under certain conditions.
d. are extremely hard.
24. Most halogens form compounds by
a. gaining an electron to form a negative ion.
b. losing an electron to form a positive ion.
c. losing protons.
d. joining with both calcium and carbon.
25. Group 18 noble gases are inert because
a. they readily form positive ions.
b. they can have either a positive or a negative charge.
c. their outermost energy level is missing one electron.
d. their outermost energy level is full.
26. Carbon and other nonmetals are found in which area of the periodic table?
a. on the left-most side
b. on the right side
c. in the middle column of the periodic table
d. in the bottom rows
27. Transition metals such as copper or tungsten form compounds by
a. gaining electrons to form negative ions.
b. losing electrons to form positive ions.
c. losing neutrons.
d. changing shape and color at various temperatures.
28. A mole is an SI base unit that describes the
a. mass of a substance.
c. volume of a substance.
b. amount of a substance.
d. electric charge of a substance.
29. If the atomic mass of carbon is 12 amu, 1 mole of pure carbon will have a mass of
a. 6 g. b. 6 mol. c. 12 g. d. 12 mol.
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30. Avogadro’s constant is defined as the number of particles in
a. one mole of a pure substance.
c. one gram of a pure substance.
b. one liter of a pure substance.
d. one kilogram of a pure substance.
31. Molar mass is defined as
a. the number of particles in 1 mole of a substance.
b. the SI base unit that describes the amount of a substance.
c. the amount of a substance necessary to have a positive charge.
d. the mass in grams of 1 mole of a substance.
32. The average atomic mass of potassium is approximately 39 amu. What is the mass of 2.0 mol of
potassium?
a. 0.39 g b. 0.78 g c. 39 g d. 78 g
33. The average atomic mass of the element cesium is approximately 133 amu. What is the mass of 3.00 mol
of cesium?
a. 0.133 g b. 133 g
c. 266 g d. 399 g
34. You have 6.50 mol of chromium, which has a molar mass of approximately 52 g/mol. What is the mass
in grams of this amount of chromium?
a. 3.38 g
b. 33.8 g
c. 338 g d. 3.38 kg
35. What is the mass in grams of 0.75 mol of sulfur, which has a molar mass of approximately 32 g/mol?
a. 16 g b. 24 g c. 32 g d. 240 g
36. You have 85.5 g of fluorine, which has a molar mass of approximately 19 g/mol. How many moles of
fluorine do you have?
a. 4.5 mol
b. 19 mol
c. 45 mol
d. 85 mol
37. A change in the color of a solution is a sign that
a. a chemical change is taking place.
b. a physical change has just occurred.
c. oxygen is present.
d. organic chemicals are present.
38. A substance that undergoes a change in a chemical reaction is
a. a product.
c. a reactant.
b. a chemical.
d. an enzyme.
39. What happens in a chemical reaction?
a. Atoms are destroyed.
c. Molecules are created.
b. Atoms are created.
d. Atoms are rearranged.
40. In an exothermic reaction, energy is transferred from
a. the reactants to the surroundings.
c. one reactant to another.
b. the surroundings to the reactants.
d. the container to the chemicals.
41. Which statement about endothermic reactions is correct?
a. Energy is always created in the form of heat.
b. Energy is transferred from the surroundings to the reactants.
c. Energy is used to force electrons to move to higher energy levels.
d. Energy is transferred from the reactants to the surroundings.
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42. Chemical energy is energy that is
a. added to a reaction in the form of heat.
b. present within atoms and molecules.
43. The energy source in photosynthesis is
a. light energy.
b. chemical energy.
c. caused by the movement of electricity.
d. released only when oxygen is present.
c. heat energy.
d. kinetic energy.
44. Most of the energy in an isooctane reaction is released in the form of
a. heat and light.
b. electrical energy
c. water. . d. sound.
45. A synthesis reaction is a reaction between at least two compounds in which
a. one breaks down into at least two products.
b. a compound is decomposed by an electric current.
c. a compound burns in the presence of oxygen.
d. a new, more complex compound is formed.
46. What kind of reaction occurs when potassium is placed in water?
a. a single-displacement reaction
c. a decomposition reaction
b. a double-displacement reaction
d. electrolysis
47. Which of the following is an example of a decomposition reaction?
a. photosynthesis
b. digestion c. polymerization
d. exchange of ions between two compounds
48. The product of the synthesis reaction between sodium and chlorine gas is
a. polyethylene.
b. carbon dioxide.
c. sodium chloride.
d. copper (II) chloride
49. When methane reacts with abundant amounts of oxygen, the products are
a. carbon dioxide and water.
c. soot and water.
b. carbon monoxide and water.
d. simple sugar and oxygen.
50. When water is broken down by electrolysis, the products are
a. water and carbon dioxide.
c. hydrogen gas and oxygen gas.
b. hydrogen and oxygen ions.
d. oxygen and methane.
51. Fragments of molecules that have at least one electron available for bonding are called
a. ions.
b. orbits.
c. protons. d. radicals.
52. In a redox reaction, the substance that accepts electrons is said to be
a. reduced. b. oxidized
c. electrified. . d. clarified.
53. When iron reacts with oxygen to form rust, each iron atom
a. loses three ions.
c. gains three ions.
b. loses three electrons.
d. gains three electrons.
54. All of the following factors may speed up a chemical reaction except
a. smaller surface area.
c. higher temperature.
b. higher pressure.
d. presence of a catalyst.
56. What could you do to make yeast dough rise more slowly?
a. Add more yeast to the mixture.
c. Add mold spores to the dough.
b. Knead the dough more vigorously.
d. Reduce the temperature.
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57. An enzyme is a special kind of catalyst that works to
a. speed up a specific biochemical reaction.
c. slow down a chemical reaction.
b. break down chemical elements.
d. maintain the correct temperature for a reaction.
58. When a chemical reaction and its reverse are occurring at the same time and at the same rate, the reaction
has achieved
a. displacement.
b. equilibrium.
c. imbalance.
d. decomposition.
59. What is the relationship between chemical equilibrium and the rates of forward and reverse reaction?
a. In equilibrium, the forward reaction rate must be greater than the reverse reaction rate.
b. In equilibrium, the forward reaction rate must be less than the reverse reaction rate.
c. In equilibrium, the forward and reverse reaction rates must be equal.
d. In equilibrium, both forward and reverse reactions must stop.
60. Le Châtelier’s principle states that increasing temperature favors a reaction that
a. releases energy as heat.
c. involves a chemical catalyst.
b. requires energy as heat.
d. involves an enzyme.
61. Increasing the concentration of one substance in an equilibrium reaction favors the reaction that
a. absorbs energy as heat.
c. produces less of that substance.
b. releases energy as heat.
d. produces more of that substance.
COMPLETION
1. The word atom comes from a Greek word that means “unable to be ____________________.”
2. The first person who suggested that matter was made up of atoms was the Greek philosopher
____________________.
3. John Dalton’s atomic theory stated that atoms of the same ____________________ are exactly alike.
4. The nucleus of an atom has a(n) ____________________ electric charge.
5. Neutrons and protons are found in the ____________________ of an atom.
6. Atoms have equal numbers of ____________________ and ____________________.
7. Bohr’s model of the atom compares electrons to ____________________.
8. According to modern atomic theory, the exact location of a(n) ____________________ is uncertain.
9. A region in which there is a high probability of finding an electron is called a(n)
____________________.
10. The order of elements in the periodic table is based on the number of ____________________ in the
nucleus.
11. The ____________________ states that when elements are listed in order of atomic number, similarities
in their properties will emerge in a regular pattern.
12. Because atoms of elements in the same group of the periodic table have the same number of
____________________, they have similar properties.
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13. Some elements are highly ____________________ because their outermost energy levels are only
partially filled.
14. The valence electron of a lithium atom is easily removed to form a lithium ____________________ with
a charge of 1+.
15. Isotopes of an element have the same atomic ____________________ but different atomic
____________________.
16. An atom of potassium has an atomic mass of 39 amu and an atomic number of 19. It therefore has
____________________ neutrons in its nucleus.
17. An element’s average atomic mass refers to the weighted average of the masses of all of its naturally
occurring ____________________.
18. Group 1 of the periodic table consists of the ____________________, a highly reactive group of
elements.
19. Atoms of alkaline-earth metals, such as calcium, have ____________________ valence electrons.
20. The ____________________ are located in the center of the periodic table.
21. The ____________________ are highly reactive elements located in Group 17 of the periodic table.
22. Noble gases are nonreactive gaseous elements that are located in Group ____________________.
23. The most familiar semiconductor, ____________________, is one of the most abundant elements in
Earth’s crust.
24. Neon is an inert gas because its outer ____________________ is full of electrons.
25. Group 17 halogens form compounds by gaining an electron and forming a ____________________.
26. The ____________________ is the SI unit that is used for counting small particles, such as atoms.
27. The ____________________ in ____________________ of 1 mol of a substance equals its molar mass.
28. The number of particles in one mole of a substance is referred to as ____________________.
29.When bread rises, this is a sign that a chemical reaction is producing ____________________.
30. A change of color is a sign that a ____________________ is taking place.
31. A sign that a chemical reaction is taking place is release of energy in the form of____________________
or ____________________.
32. The changes that are visible during a chemical reaction are signs that the ____________________ in the
reactants have been rearranged.
33. In a chemical reaction, atoms are ____________________, but they are not created or destroyed.
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34. A chemical reaction that transfers energy from the reactants to the surroundings is referred to
as____________________.
35. A(n) ____________________ reaction is one in which heat is transferred from the surroundings to the
reactants.
36. Photosynthesis is an example of a(n) ____________________ chemical reaction in which plants use
sunlight to make glucose and oxygen.
37. ____________________ is an exothermic reaction in which living things produce light.
38. The general formula for a synthesis reaction is ____________________.
39. In a(n) ____________________ reaction, the reactants are broken down into other substances.
40. In a combustion reaction, ____________________ is used to make reactants burn.
41.When methane burns in the presence of insufficient oxygen, the products of the reaction are water and
____________________.
42. Alkali metals react violently with water to form metal ions, hydroxide ions, and
____________________.
43. Aluminum undergoes a single-displacement reaction with copper (II) sulfate to form aluminum sulfate
and ____________________.
44. A substance is said to be ____________________ when it gains electrons.
45. Radicals react quickly to form covalent bonds with nearby substances because they have
____________________ available for bonding.
46. Balance the following chemical equation by filling in the correct coefficient on the right-hand side. H2 +
Cl2 ____________________ HCl
47. Balance the following chemical equation by filling in the correct coefficients.
____________________ KI + Br2 ____________________ KBr + I2
48. Suppose you were producing zinc chloride by the reaction Zn + 2HCl ZnCl2 + H2. If you started with 4
moles of zinc, you would need ____________________ moles of hydrogen chloride and you would produce
____________________ moles of zinc chloride.
49. In the chemical equation CH4 + O2 CO2 + 2H2O, for every one mole of carbon dioxide you produced,
you would have ____________________ mole(s) of water.
50. The law of definite proportions states that a compound always contains the same
____________________ in the same ____________________.
51. You are producing magnesium oxide by the reaction 2Mg + O2 2MgO. If you start out with 6 moles
of magnesium, you will need ____________________ moles of oxygen, and you will produce
____________________ moles of magnesium oxide.
52. In the chemical equation H2 + Cl2 2HCl, the mole ratios are ____________________.
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53. In the chemical equation FeS + 2HCl FeCl2 + H2S, the mole ratios are ____________________.
54. In a chemical reaction, the combined molar masses of the ____________________ equals the combined
molar masses of the ____________________.
55. A catalyst that slows a reaction is called a(n) ____________________.
56. An enzyme is a(n) ____________________ that acts as a(n) ____________________ in a chemical
reaction that takes place in a living thing.
57. In a state of equilibrium, a reaction and its reverse occur at the same ____________________ and
at the same ____________________.
58. Equilibrium is achieved when the ____________________ and ____________________ reactions
continue to take place at the same rate.
59. When a reaction is at equilibrium, increasing the pressure favors the reaction that produces
____________________.
60. When a reaction is at equilibrium, increasing the temperature favors the reaction that
____________________.
ESSAY
1. Explain why atoms have no electric charge even though they are made up of charged particles.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------2. Explain how isotopes affect an element’s average atomic mass.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------3. Explain why energy is necessary to chemical reactions, and describe some common sources of energy.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------4. “Photosynthesis, the basis for all life on Earth, is an endothermic chemical reaction.” Explain.
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