Chemistry Reference
In-Depth Information
TABLE 2.8
Some Essential Trace Elements and Their Oxidation States
Transition Metal
Oxidation Number
Molybdenum
III
IV
V
VI
Manganese
II
III
IV
VI
VII
Iron
II
III
IV
VI
Cobalt
II
III
IV
Nickel
II
III
Copper
I
II
III
Zinc
II
2.3.3
A
tomic
r
Adii
The atomic radii describe the characteristic size of the neutral and isolated atoms
that are not involved in any kind of bonds.
The radius of the free atom is considered
the distance from the nucleus to the point of maximum electron radial density of the
occupied atomic orbital.
The atomic radius cannot be determined directly. The electron cloud is diffuse
due to the undulatory waveform nature of the electron, making it impossible to assign
a well-defined outer structure to the atom. One indirect method for the determination
of the relative atomic radius is the use of the formula derived from Bohr's atomic
model. The formula for the hydrogen atom is the following:
2
h
πme
ε
0
r=
= 0.53
Å
(2.12)
H
2
where all measures are universal constants, namely:
•
ε
0
is the permittivity of vacuum (8.85*10
−12
F/m),
•
h is Planck's constant (6.63*10
−34
Js),
