CHEMISTRY 121
HWCH#4
TRO ED5
34,38,44, 50,54,60,66,72,74,76,78,82,86,90,94,98,102
4-34
a.
b.
c.
d.
e.
False, neutral atoms have equal numbers of protons and electrons.
True
True
True
4-38
4-38
(Mass of 1 electron)X –2( mass of 1 neutron)
(mass of 1 electron)
X=
X=
2(1.67262X10-27 kg ) + 2(1.67943X10-27kg)
0.00091X10-27 kg
2(mas o 1 proton + 2(mass of 1 neutron
Mass of 1 electron
= 7.4 X 103
4-44
a.
b.
c.
d.
e.
22
3
92
35
9
4-50
Element Name
Aluminum
Iodine
Antimony
Sodium
Radon
Lead
Element Symbol
Al
I
Sb
Na
Rn
Pb
4-54 Nonmetals gain electrons in reactions therefore
a. Nitrogen
b. Iodine
c.
4-60
c.
d.
Potassium
Lithium
Atomic Number
13
53
51
11
86
82
4-66
The elements most like magnesium would be those elements in the same group #2
because they all have similar physical and chemic al properties. Therefore, the answer is
d) calcium
4-72
a. Mg → Mg2+ + 2eb. Ba →Ba2+ + 2ec. I + e- → Id. Al → Al3+ + e4-74
a. Tungsten ion charge = 74(1+)- 68(1-) = 6+
b. Tellurium ion charge = 52(1+)- 54(1-) = 2c. Nitrogen ion charge = 7(1+)- 6108(1-) = 3d. Barium ion charge = 56(1+)- 54(1-) = 2+
e.
4-76
The number of protons is determined using the atomic number of each element. The
number of electrons is determined by examining the net charge on the ion.
a. 13p + 10e- = 3+
b. 16p + 18e- = 2c. 53p + 54e- =1d. 47p + 46e- = 1+
4-78
a.
b.
c.
d.
False; the Fe+ ion contains 26 protons and 25 electrons
False: The Cs+ ion contains 55 protons and 54 electrons.
False: The Se2- ion contains 34 protons and 36 electrons.
True
4-82
a. Iodine is in group 17, therefore it will gain 1 electron.
b. Ba is in group 2, therefore it will lose 2 electrons.
c. Ce is in group 1; therefore it will lose 1 electron
d. Se is in group 16; therefore it will gain 2 electrons
4-86
Neutrons = mass number – atomic number
a. 59-28 =31
b. 235-92= 143
c. 45-21 = 25
d. 42-18 = 24
4-90
a. 235
92 U
3
b.
52
23 V
c
.
32
15 P
144
d. 54 Xe
4-94
P= 94; n=145
239
Pu
94
4-98
a. 107.87 amu
b. 100.00 – 51.84 = 48.16%
106.905 x 0.5184 + 0.4816X = 107.87
0.4816 X = 107.87 – 55.419552
0.4816 X = 52.4504
X = 109.91 amu
4-102
proton
1.6 X 10-19 C
10-3 C
mC
398 mC
= 2.5 x 1018 protons