47374_04_p25-32.qxd 2/9/07 7:50 AM Page 25
4
Atoms and Elements
4.1
a. Cu
e. Fe
b. Si
f. Ba
c. K
g. Pb
d. N
h. Sr
4.2
a. O
e. H
b. Li
f. Ne
c. S
g. Sn
d. Al
h. Au
4.3
a. carbon
e. fluorine
b. chlorine
f. argon
c. iodine
g. zinc
d. mercury
h. nickel
4.4
a. helium
e. calcium
b. phosphorus
f. bromine
c. sodium
g. cadmium
d. magnesium
h. silicon
4.5
a.
b.
c.
d.
sodium (Na) and chlorine (Cl)
calcium (Ca), sulfur (S), and oxygen (O)
carbon (C), hydrogen (H), chlorine (Cl), nitrogen (N), and oxygen (O)
calcium (Ca), carbon (C), and oxygen (O)
4.6
a.
b.
c.
d.
hydrogen (H) and oxygen (O)
sodium (Na), hydrogen (H), carbon (C), and oxygen (O)
sodium (Na), oxygen (O), and hydrogen (H)
carbon (C), hydrogen (H), and oxygen (O)
4.7
a.
b.
c.
d.
C, N, and O are in Period 2.
He is the element at the top of Group 8A (18).
The alkali metals are the elements in Group 1A (1).
Period 2 is the horizontal row of elements that ends with neon (Ne).
4.8
a. Group 1A (1)
4.9
a. alkaline earth metal
d. alkali metal
b. Period 2
4.10 a. noble gas
d. halogen
c. Group 8A (18)
d. Group 7A (17)
b. transition element
e. halogen
c. noble gas
b. alkaline earth metal
e. alkaline earth metal
c. transition element
4.11 a. C
b. He
c. Na
d. Ca
e. Al
4.12 a. Be
b. P
c. Kr
d. I
e. Ge
4.13 On the periodic table, metals are located to the left of the heavy zigzag line, nonmetals are elements
to the right, and metalloids (B, Si, Ge, As, Sb, Te, Po, and At) are located along the line.
a. metal
b. nonmetal
c. metal
d. nonmetal
e. nonmetal
f. nonmetal
g. metalloid
h. metal
4.14 a. metal
e. nonmetal
b. metal
f. nonmetal
c. nonmetal
g. nonmetal
d. metalloid
h. metal
4.15 a. electron
b. proton
c. electron
d. neutron
4.16 a. neutron
b. proton and neutron
c. electron
d. electron
4.17 Rutherford determined that the two most massive subatomic particles, protons and neutrons, are
located in a very small, central region of the atom called the nucleus.
25
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Chapter 4
4.18 Because protons are present in the nucleus of every element and protons are the positively charged
subatomic particles.
4.19 Selection b (a proton and an electron) is the only one with a pair of particles having opposite
charges.
4.20 Answers a (two protons) and c (two electrons) are pairs of particles having the same charge.
4.21 In the process of brushing your hair on a dry day, unlike charges that attract develop on the hair
and brush.
4.22 Because the clothes cling to each other, there must be opposite (unlike) electrical charges on the
clothing.
4.23 The atomic number is equal to the number of protons. The mass number is the sum of the protons
and neutrons.
a. atomic number
b. both
c. mass number
d. atomic number
4.24 a.
b.
c.
d.
number of protons and electrons, if a neutral atom
number of particles (protons plus neutrons) in the nucleus
number of neutrons
nothing useful
4.25 a. lithium, Li
e. neon, Ne
b. fluorine, F
f. silicon, Si
c. calcium, Ca
g. iodine, I
d. zinc, Zn
h. oxygen, O
4.26 a. hydrogen, H
e. bromine, Br
b. sodium, Na
f. silver, Ag
c. potassium, K
g. phosphorus, P
d. iron, Fe
h. helium, He
4.27 a. 12
b. 30
c. 53
d. 19
4.28 a. 6
b. 9
c. 20
d. 16
4.29
Name
of Element
Symbol
Atomic
Number
Mass
Number
Number
of Protons
Number of
Neutrons
Number of
Electrons
Aluminum
Magnesium
Potassium
Sulfur
Iron
Al
Mg
K
S
Fe
13
12
19
16
26
27
24
39
31
56
13
12
19
16
26
14
12
20
15
30
13
12
19
16
26
Symbol
Atomic
Number
Mass
Number
Number
of Protons
Number of
Neutrons
Number of
Electrons
N
Ca
Sr
Si
Ba
7
20
38
14
56
15
42
88
30
138
7
20
38
14
56
8
22
50
16
82
7
20
38
14
56
4.30
Name
of Element
Nitrogen
Calcium
Strontium
Silicon
Barium
4.31 a. Because the atomic number of aluminum is 13, every Al atom has 13 protons. An atom of aluminum (mass number 27) has 14 neutrons (27 13 14 n). Neutral atoms have the same
number of protons and electrons: 13 protons, 14 neutrons, and 13 electrons.
26
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Atoms and Elements
b. Because the atomic number of chromium is 24, every Cr atom has 24 protons. An atom of
chromium (mass number 52) has 28 neutrons (52 24 28 n). Neutral atoms have the same
number of protons and electrons: 24 protons, 28 neutrons, and 24 electrons.
c. Because the atomic number of sulfur is 16, every S atom has 16 protons. An atom of sulfur
(mass number 34) has 18 neutrons (34 16 18 n). Neutral atoms have the same number of
protons and electrons: 16 protons, 18 neutrons, and 16 electrons.
d. Because the atomic number of iron is 26, every Fe atom has 26 protons. An atom of iron (mass
number 56) has 30 neutrons (56 26 30 n). Neutral atoms have the same number of protons
and electrons: 26 protons, 30 neutrons, and 26 electrons.
4.32 a.
b.
c.
d.
1 proton, 1 neutron, 1 electron
7 protons, 7 neutrons, 7 electrons
14 protons, 12 neutrons, 14 electrons
30 protons, 40 neutrons, 30 electrons
4.33 a.
31
15P
b.
4.34 a.
18
8O
b. 94Be
80
35Br
c.
27
13Al
d.
35
17Cl
c.
56
26Fe
d.
24
11Na
33
34
36
4.35 a. 32
16S
16S
16S
16S
b. They all have the same atomic number (the same number of protons and electrons).
c. They have different numbers of neutrons, which is reflected in their mass numbers.
d. The atomic mass of sulfur on the periodic table is the average atomic mass of all the naturally
occurring isotopes of sulfur.
86
87
88
4.36 a. 84
38Sr
38Sr
38Sr
38Sr
b. They all have the same atomic number (the same number of protons and electrons).
c. They have different numbers of neutrons, which is reflected in their mass numbers.
d. The atomic mass of strontium on the periodic table is the average atomic mass of all the naturally occurring isotopes of strontium.
4.37 The mass of an isotope is the mass of an individual atom. The atomic mass is the weighted average of all the naturally occurring isotopes of that element.
4.38 The mass number gives the number of protons and neutrons in an atom; the atomic number gives
the number of protons.
4.39 Because the atomic mass of copper is closer to 63 amu, there are more atoms of 63Cu.
4.40 The mass of F on the periodic table should be very close to 19 amu.
4.41 Because the atomic mass of iron is 55.85 amu, the most abundant isotope is 56Fe.
4.42 The atomic mass of Zn is the weighted average of the masses of the five isotopes.
4.43 68.926 amu 39.90
60.10
70.925 amu 69.72 amu
100
100
4.44 63.55 amu
4.45 The electrons surrounding a nucleus have specific energies. Electrons with similar energies will
be found grouped together within a specific energy level.
4.46 The first energy level is filled with 2 electrons. The second energy level can hold a maximum of 8
electrons. Because we are only considering the first 20 elements, the third energy level will have 8
electrons and the fourth energy level will have only 2 electrons in it.
4.47 a. 8
b. 5
c. 8
d. 0
e. 8
4.48 a. 0
b. 6
c. 5
d. 8
e. 0
27
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Chapter 4
4.49 a. 2, 4
b. 2, 8, 8
c. 2, 8, 6
d. 2, 8, 4
e. 2, 8, 3
f. 2, 5
4.50 a. 2, 8, 5
b. 2, 8
c. 2, 6
d. 2, 8, 8
e. 2, 8, 3
f. 2, 8, 4
4.51 a. Li
b. Mg
c. H
d. Cl
e. O
4.52 a. N
b. S
c. C
d. Ar
e. Al
4.53 a. boron, B: 2, 3 aluminum: 2, 8, 3
b. 3
c. Group 3A (13)
4.54 a. fluorine, F: 2, 7 chlorine: 2, 8, 7
b. 7
c. Group 7A (17)
4.55 a. 2 e, Group 2A (2)
d. 5 e, Group 5A (15)
b. 7 e, Group 7A (17)
e. 2 e, Group 2A (2)
c. 6 e, Group 6A (16)
f. 7 e, Group 7A (17)
4.56 a. 1 e, Group 1A (1)
d. 8 e, Group 8A (18)
b. 4 e, Group 4A (14)
e. 4 e, Group 4A (14)
c. 8 e, Group 8A (18)
f. 1 e, Group 1A (1)
4.57 The number of dots is equal to the number of valence electrons as indicated by the group number.
a. Sulfur has 6 valence electrons S
Group 6A (16)
b. Nitrogen has 5 valence electrons
N
c. Calcium has 2 valence electrons
Ca
Group 5A (15)
Group 2A (2)
d. Sodium has 1 valence electron Na
Group 1A (1)
e. Potassium has 1 valence electron K
Group 1A (1)
4.58 a. 4A (14), C
b. 6A (16), O
d. 1A (1), Li
4.59 a. M
4.60 a.
Nm
e. 7A (17),
b.
M
b.
Nm
c. 7A (17),
F
Cl
4.61 Alkali metals are members of Group 1A (1), and each has 1 valence electron.
4.62 Halogens are members of Group 7A (17), and each has 7 valence electrons.
4.63 a. The ionization energy decreases going down a group: Br, Cl, F
b. Going across a period from left to right, the ionization energy generally increases: Na, Al, Cl
c. The ionization energy decreases going down a group: Cs, K, Na
4.64 a. C, O, N
b. S, P, Cl
c. As, P, N
4.65 a. Br, which is above I in Group 7A (17), has a higher ionization energy than I.
b. Al has a higher ionization energy than K because ionization energy increases going left to right
and decreases going down a group.
c. P has a higher ionization energy than Si because ionization energy increases going left to right
across a period.
4.66 a. Ne
b. Br
c. Ca
4.67 a. false
b. true
c. true
4.68 a.
b.
c.
d.
e.
28
d. false
X is Cl, chlorine. This isotope has 17 protons and 20 neutrons.
X is Fe, iron. This isotope has 26 protons and 30 neutrons.
X is Sn, tin. This isotope has 50 protons and 66 neutrons.
X is Sn, tin. This isotope has 50 protons and 74 neutrons.
X is Cd, cadmium. This isotope has 48 protons and 68 neutrons.
c and d are both isotopes of Sn, tin.
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Atoms and Elements
4.69 a.
b.
c.
d.
Both have 20 neutrons.
Both have 16 protons.
Not the same.
Both have 22 neutrons.
4.70
Isotope
28
Number of protons
Number of neutrons
Number of electrons
Atomic number
Mass number
4.71 a. 94Be
b.
29
Si
14
14
14
14
28
11
5B
30
Si
Si
14
15
14
14
29
c.
13
6C
14
16
14
14
30
d.
10
5B
e.
12
6C
The atoms b and d are isotopes of boron; c and e are isotopes of carbon.
4.72 a. metal
b. metalloid
c. nonmetal
d. metalloid
4.73 a. 3, Li
b. 86, Rn
c. 24.31, Mg
d. 19.00, F
4.74 a. 32, Ge
b. 83, Bi
c. 39.10 amu, K
d. 210, At
e. nonmetal
4.75 Any element with a two-letter symbol has the first letter capitalized and the second letter in lowercase. CO would indicate a compound made of the two elements carbon and oxygen.
4.76 a.
c.
e.
g.
Incorrect. The symbol for copper is Cu.
Correct as written.
Incorrect. The symbol for potassium is K.
Correct as written.
4.77 a. Mg, magnesium
b. Br, bromine
4.78 a. Group 1A (1), Period 4
c. Group 4A (14), Period 2
b.
d.
f.
h.
Incorrect. The symbol for silicon is Si.
Incorrect. The symbol for fluorine is F.
Correct as written.
Incorrect. The symbol for lead is Pb.
c. Al, aluminum
d. O, oxygen
b. Group 5A (15), Period 3
d. Group 8A (18), Period 2
4.79 Any two of the following in each part are correct responses:
a. Group 7A (17), fluorine, chlorine, bromine, iodine, or astatine
b. Group 8A (18), helium, neon, argon, krypton, xenon, or radon
c. Group 1A (1), lithium, sodium, potassium, rubidium, cesium, or francium, but not hydrogen
d. Group 2A (2), beryllium, magnesium, calcium, strontium, barium, or radium
4.80 a. metal
d. nonmetal
b. metal
e. metal
c. metal
f. nonmetal
4.81 a.
b.
c.
d.
e.
False. A proton has a positive charge.
False. The neutron has about the same mass as a proton.
True
False. The nucleus is the tiny, dense, central core of an atom.
True
4.82 a.
b.
c.
d.
e.
True
True
False. The charge of the electron is equal but opposite to the charge of the proton.
False. The proton and the neutron have about the same mass.
False. The atomic number is the number of protons.
4.83 a. protons
b. protons
c. alkali metals
4.84 a. mass
b. halogens
c. metals
29
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Chapter 4
4.85 a. lithium, Li
e. tin, Sn
b. fluorine, F
f. cesium, Cs
c. calcium, Ca
g. gold, Au
d. arsenic, As
h. oxygen, O
4.86 a. hydrogen, H
e. bromine, Br
b. sodium, Na
f. silver, Ag
c. chromium, Cr
g. bismuth, Bi
d. iron, Fe
h. uranium, U
4.87 a. 25 protons, 25 electrons
c. 53 protons, 53 electrons
e. 19 protons, 19 electrons
b. 30 protons, 30 electrons
d. 12 protons, 12 electrons
4.88 a. 6 protons, 6 electrons
c. 27 protons, 27 electrons
e. 48 protons, 48 electrons
b. 20 protons, 20 electrons
d. 17 protons, 17 electrons
4.89 a.
b.
c.
d.
e.
13 protons, 14 neutrons, 13 electrons
24 protons, 28 neutrons, 24 electrons
16 protons, 18 neutrons, 16 electrons
26 protons, 30 neutrons, 26 electrons
54 protons, 82 neutrons, 54 electrons
4.90 a.
b.
c.
d.
e.
10 protons, 12 neutrons, 10 electrons
53 protons, 74 neutrons, 53 electrons
35 protons, 40 neutrons, 35 electrons
55 protons, 78 neutrons, 55 electrons
78 protons, 117 neutrons, 78 electrons
4.91 a. 9Be
4.92 a.
27
Al
4.93
b.
26
Mg
c.
46
d.
70
Zn
b.
58
Fe
c.
88
d.
72
As
Name
Nuclear
Symbol
Sulfur
Zinc
Magnesium
Radon
34
16S
70
30Zn
26
12Mg
220
86Rn
Name
Nuclear
Symbol
Potassium
Vanadium
Cadmium
Barium
41
19K
51
23V
112
48Cd
138
56Ba
4.94
Ca
Sr
e.
63
Cu
Number of
Protons
Number of
Neutrons
Number of
Electrons
16
30
12
86
18
40
14
134
16
30
12
86
Number of
Protons
Number of
Neutrons
Number of
Electrons
19
23
48
56
22
28
64
82
19
23
48
56
4.95 a. 26 protons, 30 neutrons, 26 electrons
b. 51
26Fe
c. 51
24Cr
4.96 No. The atomic mass is the weighted average of the eight naturally occurring isotopic masses.
4.97 a.
b.
c.
d.
30
16
8X
16
8X
16
8X
18
10X
16
8X
17
8X
17
8X
16
9X
18
8X
18
10X
18
8X
18
8X
All have 8 protons.
All are isotopes of oxygen.
Both have mass number of 16.
Both have mass number of 18.
Both have 8 neutrons.
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Atoms and Elements
66
67
68
70
4.98 a. 64
30Zn
30Zn
30Zn
30Zn
30Zn
b. All these isotopes contain 30 protons and 30 electrons. Zinc-64 contains 34 neutrons, zinc-66
contains 36 neutrons, zinc-67 contains 37 neutrons, zinc-68 contains 38 neutrons, and zinc-70
contains 40 neutrons.
4.99 a. 82 protons, 126 neutrons, 82 electrons
b. 214Pb
c. 214Bi, bismuth
4.100 a. 47 protons, 60 neutrons, 47 electrons
b. 109Ag
c. 109Cd, cadmium
4.101 a. N, Group 5A (15), electron arrangement
2, 5
b. Na, Group 1A (1) electron arrangement
2, 8, 1
c. S, Group 6A (16), electron arrangement
2, 8, 6
d. B, Group 3A (13), electron arrangement
2, 3
4.102 a. C, Group 4A (14), electron arrangement
2, 4
b. Si, Group 4A (14), electron arrangement
c. P, Group 5A (15), electron arrangement
N
Na
S
B
C
2, 8, 4
2, 8, 5
d. Ar, Group 8A (158), electron arrangement
2, 8, 8
Si
P
Ar
4.103 Calcium has a greater net nuclear charge than K. The least tightly bound electron in Ca is further
from the nucleus than in Mg and needs less energy to remove.
4.104 The least tightly bound electron in Cl is further from the nucleus than in F and needs less energy
to remove. Chlorine has 7 protons and sulfur has 6, so it is easier to remove the valence electron
from sulfur.
4.105 a.
b.
c.
d.
Na is on the far left of the heavy zigzag line. Na is a metal.
F at the top of Group 7A (17) and to the far right in Period 2 has the highest ionization energy.
Na has the lowest ionization energy and loses an electron most easily.
Cl is found in Period 3 in Group 7A (17).
4.106 a. Kr
b. Ca
c. Kr
d. Ca
4.107 1.40 /100 203.97 amu 24.10 /100 205.97 amu 22.10/100 206.98 amu
52.40/100 207.98 amu 207.22 amu
4.108 43.0 /100 112.90 amu 95.70 /100 M115 114.8 amu
M115 119.7 amu
4.68
3.09
92.23
28.976 amu 29.974 amu 100
100
100
25.80 amu 1.36 amu 0.9262 amu
28.09 amu
4.109 27.977 amu 4.110 42.70 /100 122.90 amu 57.30 /100 M121 121.75 amu
M121 120.89 amu
31
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Chapter 4
4.111 1 in. 2.54 cm
1 atom
8.09 107 atoms
1 in.
3.14 108 cm
4.112 200 cm3 32
11.3 g
1 atom
6.6 1022 atom
3
cm
3.4 1022 g