Element
Symbol
-24
number
amusa
Neutron In nucleus
0
1.009
1.675 X 10
-28
Actinium
Ac
89
Electron
Outside nucleus
-1
0.00549
9.11 X 10
Aluminum
Al
13
26.9815
Americium
Am
95
a amu = atomic mass unit, where 1 amu = 1.66 X 10 -24 gram.
Antimony
Sb
51
121.75
Argon
Ar
18
39.948
Arsenic
As
33
74.9216
Astatine
At
85
Barium
Ba
56
atomic weights are used for the mass of a particular element.
137.34
Table 2.2 contains symbols, atomic numbers, and atomic weights Berkelium
Bk
97
Beryllium
Be
4
for the elements.
9.0122
Chemical reactivity, and therefore pyrotechnic and explosive Bismuth
Bi
83
208.980
Boron
behavior, is determined primarily by the tendency for each eleB
5
10.811
Bromine
Br
ment to gain or lose electrons during a chemical reaction. Cal-35
79.909
Cadmium
Cd
culations by theoretical chemists, with strong support from ex-48
112.40
Calcium
Ca
perimental studies, suggest that electrons in atoms are found in 20
40.08
Californium
Cf
98
"orbitals," or regions in space where they possess the lowest possible energy - close to the nucleus but away from other neg-Carbon
C
6
12.01115
Cerium
Ce
58
140.12
atively-charged electrons.
As electrons are placed into an atom,
Cesium
energy levels close to the positive nucleus are occupied first, Cs
55
132.905
Chlorine
and the higher energy levels are then successively populated.
Cl
17
35.453
Chromium
Cr
Extra stability appears to be associated with completely filled 24
51.996
Cobalt
Co
27
levels, termed "shells." Elements with completely filled shells 58.9332
Copper
Cu
29
include helium (atomic number 2), neon (atomic number 10), 63.54
Curium
Cm
96
argon (atomic number 18), and krypton (atomic number 36).
Dysprosium
Dy
66
162.50
These elements all belong to a group called the "inert gases,"
Einsteinium
and their virtual lack of any chemical reactivity provides sup-Es
99
Erbium
Er
port for the theory of filled-shell stability.
68
167.26
Europium
Eu
63
Other elements show varying tendencies to obtain a filled 151.96
Fermium
Fm
100
shell by the sharing of electrons with other atoms, or by the Fluorine
F
9
actual gain or loss of electrons to form charged species, called 18.9984
Francium
Fr
87
ions.
For example, sodium (symbol Na, atomic number 11) Gadolinium
Gd
readily loses one electron to form the sodium ion, Na+, with 10
64
157.25
Gallium
Ga
31
69.72
electrons.
By losing one electron, sodium has acquired the same Germanium
Ge
number of electrons as the inert gas neon, and it has become a 32
72.59
Gold
Au
79
very stable chemical species. Fluorine (symbol F, atomic num-196.967
Hafnium
ber 9) readily acquires one additional electron to become the Hf
72
178.49
Helium
He
2
fluoride ion, F - .
This is another 10-electron species and is
4.0026
VI J
10
Chemistry of Pyrotechnics
Basic Chemical Principles
11
TABLE 2.2 (continued)
TABLE 2.2 (continued)
Atomic
Atomic weight,
Atomic
Atomic weight,
Element
Symbol
number
amusa
Element
Symbol
number
amus a
Holmium
Ho
67
164.930
Rubidium
Rb
37
85.47
Hydrogen
H
1
1.00797
Ruthenium
Ru
44
101.07
Indium
In
49
114.82
Samarium
Sm
62
150.35
Iodine
I
53
126.9044
Scandium
Sc
21
44.956
Iridium
Ir
77
192.2
Selenium
Se
34
78.96
Iron
Fe
26
55.847
Silicon
Si
14
28.086
Krypton
Kr
36
83.80
Silver
A g
4 7
107.870
Lanthanum
La
57
138. 91
Sodium
Na
11
22.9898
Lead
Pb
82
207.19
Strontium
Sr
38
87.62
Lithium
Li
3
6.939
Sulfur
S
16
32.064
Lutetium
Lu
71
174. 97
Tantalum
Ta
73
180.948
Magnesium
Mg
12
24.312
Technetium
Tc
43
Manganese
Mn
25
54.9380
Tellurium
Te
52
127.60
Mendelevium
Md
101
Terbium
Tb
65
158.924
Mercury
Hg
80
200.59
Thallium
T1
81
204.37
Molybdenum
Mo
42
95.94
Thorium
T h
90
232.038
Neodymium
Nd
60
144.24
Thulium
Tm
6 9
168.934
Neon
Ne
10
20.183
Tin
Sn
50
118.69
Neptunium
Np
93
Titanium
Ti
22
47.90
Nickel
Ni
28
58.71
Tungsten
W
74
183.85
Niobium
Nb
41
92.906
Uranium
U
92
238.03
Nitrogen
N
7
14.0067
Vanadium
V
2 3
50.942
Nobelium
No
102
Xenon
Xe
54
131.30
Osmium
Os
76
190.2
Ytterbium
Yb
70
173.04
Oxygen
0
8
15.9994
Yttrium
Y
39
88.905
Palladium
Pd
46
106.4
Zinc
Zn
30
65.37
Phosphorus
P
15
30.9738
Zirconium
Zr
40
91.22
Platinum
Pt
78
195.09
a
-24
Plutonium
Pu
94
amu = atomic mass unit, where 1 amu = 1.66 X 10
gram.
Polonium
Po
84
Potassium
K
19
39.102
Praseodymium
Pr
59
140.907
Promethium
Pm
61
quite stable.
Other elements display similar tendencies to gain Protactinium
Pa
91
or lose electrons to acquire "inert gas" electron configurations Radium
Ra
88
by becoming positive or negative ions. Many chemical species found in nature are ionic compounds. These are crystalline Radon
Rn
86
Rhenium
Re
75
186.2
solids composed of interpenetrating lattices of positive and neg-Rhodium
Rh
45
102.905
ative ions held together by electrostatic attraction between these Oppositely-charged particles.
Table salt, or sodium chloride, is