Chemistry Reference
In-Depth Information
1.8
Atomic radius
Ionic radius
Covalent radius
1.6
1.4
1.2
1
Å
0.8
0.6
0.4
0.2
0
H
e
i
e
B
C
N
O
F
Ne
Elements
FIGURE 2.8
The variation of atomic radii, ionic radii, and covalent radii for the elements
in periods 1 and 2.
2
Atomic radius
Ionic radius
Covalent radius
1.8
1.6
1.4
1.2
1
Å
0.8
0.6
0.4
0.2
0
Na
Mg
Al
Si
P
S
Cl
Ar
Elements
FIGURE 2.9
The variation of atomic radii, ionic radii, and covalent radii for the elements
in period 3.
minimum quantity of energy required for the removal of one or more electrons from an
atom or from an isolated ion that exists in a gaseous state. For this endothermic process,
the ionization energy is expressed in Joules or electron volts (1eV = 1.602 *10
−19
J). For
example, for the hydrogen atom to lose an electron requires 1310kJ/mol:
H (g) + 1310 kJ → H
+
(g) + e
−
(2.14)
Each electron in an atom corresponds to a specific ionization energy. Thus, an ini-
tial energy IE
1
is required to remove the first electron, which is the weakest bound in
