Download Concept Reviews Answer sheet Section: matter and Energy 1. a

Concept Reviews Answer sheet
SECTION: MATTER AND ENERGY
1. a. liquid
b. gas
c. solid
d. plasma
2. The sugar molecules will have a lower speed on average than the water molecules because the sugar molecules are
more massive than the water molecules. As the temperature of the mixture increases, the speed of all of the
molecules will increase.
3. Coffee at 38°C has more kinetic energy than coffee at 34°C. Although there is less tea than coffee, the
temperature of the tea is greater, so the tea has more average kinetic energy than the coffee.
4. The temperature, and therefore the kinetic energy of the particles in 0.5 L of coffee and 0.25 L of coffee are the
same, but there are more particles in 0.5 L of coffee, so the total thermal energy is greater.
5. a. 6 cm3 of ice is a solid, so it retains its shape and has a volume of 6 cm3.
b. The melted ice is a liquid. The liquid takes the shape of the beaker, but retains its volume.
c. The evaporated water is a gas, and has no definite shape and no definite volume.
SECTION: FLUIDS
1. An object in a fluid medium displaces a set amount of fluid upon immersion. Archimedes’ principle states that
the weight of the displaced fluid is equal to the buoyant force exerted on the object.
2. The buoyant force exerted on the wood is equal to the weight of the wood.
3. 150,000 Pa
4. A fluid in equilibrium contained in a vessel exerts a pressure of equal intensity in all directions.
5. 33,250 N
6. As the speed of a moving fluid increases, its pressure decreases.
SECTION: BEHAVIOR OF GASES
1. a. Boyle’s law
b. Charles’s law
c. Gay-Lussac’s law
2. Solids have molecules fixed in relation to each other. Liquids have molecules capable of sliding past each other,
but still stick together. Gases have molecules that are rarely in contact with each other. A substance as a solid
has a definite volume and shape. The same substance as a liquid has a definite volume but takes the shape of its
container. The same substance as a gas has no definite shape or volume.
3. a
4. c
5. d
6. Either its pressure or volume must also change. Alternatively, both may change. The amplitude and direction of
the changes depends on the original temperature change.
SECTION: THE DEVELOPMENT OF ATOMIC THEORY
1. The word “atom” comes from atomos, a Greek word that means “unable to be cut or divided.”
2. Dalton proposed that each element is made up of unique atoms that cannot be subdivided, that all of the atoms of an
element are the same, and that atoms of different elements could join to form compounds.
3. In Thomson’s model of the atom, the mass and positive charge of an atom are evenly distributed, and electrons
are scattered throughout the atom. In Rutherford’s model, negative electrons orbit the atom’s positively charged
nucleus.
4. Thomson discovered that atoms contain electrons. Rutherford discovered that an atom’s positive charge is
concentrated in the nucleus.
SECTION: THE STRUCTURE OF ATOMS
1. A large counting unit like the mole is used to count atoms because atoms are too small to count individually.
2. Check students’ drawings. Drawings should include two protons and two neutrons clustered in the nucleus and
two electrons moving around outside the nucleus. Protons have a +1 charge, electrons have a –1 charge, and
neutrons have a charge of zero.
proton mass = 1.67  10–27
electron mass = 9.11  10–31
neutron mass = 9.11  10–27
3. The atomic number is the number of protons found in the nucleus of an atom. The mass number is the total
number of protons plus neutrons found in the nucleus.
4.
Isotope
Mass number p
protium
A=1
1
deuterium A = 2
1
tritium
A=3
1
n
0
1
2
1
1
1
5. a. 12 g of Ne
b. 658 g of Xe
c. 150 g of Se
d. 650 g of Au
Page 7
Isotope
Name
Isotope
Symbol
1.
calcium-40
40
20
2.
magnesium-24
3.
Hydrogen-3
4.
Gold-197
197
79
5.
Iron-56
56
26
6.
Mercury
7.
Chlorine
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Atomic
Number
Mass
Number
# of
Protons
# of
Neutrons
# of
Electrons
20
40
20
20
20
Au
12
24
12
12
12
H
1
3
1
2
1
79
197
79
118
79
26
56
26
30
26
201
80
Hg
80
201
80
121
80
35
17
Cl
17
35
17
18
17
Ca
197
79
3
1
Au
Fe
Page 5 Graphic Organizer Answers
Element
Atomic #, mass #, atomic mass
# of protons, number of protons plus neutrons, isotopes
Electrons, same number of protons, different numbers of neutrons
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