331Characteristics
Chemical
Like other groups, the members of this family show patterns in its electron configuration,
especially the outermost shells resulting in trends in chemical behavior:
Z Element No. of electrons/shell
6 Carbon 2, 4
14 Silicon 2, 8, 4
32 Germanium 2, 8, 18, 4
50 Tin 2, 8, 18, 18, 4
82 Lead 2, 8, 18, 32, 18, 4
114 Flerovium 2, 8, 18, 32, 32, 18, 4 (predicted)Each of the elements in this group has 4 electrons in its outer energy level. The last orbital
of all these elements is the p^2 orbital. In most cases, the elements share their electrons.
The tendency to lose electrons increases as the size of the atom increases, as it does with
increasing atomic number.
Carbon alone forms negative ions, in the form of carbide (C4−) ions. Silicon and
germanium, both metalloids, each can form +4 ions. Tin and lead both are metals while
flerovium is a synthetic, radioactive (its half-life is very short), element that may have a
few noble gas-like properties, though it is still most likely a post-transition metal. Tin and
lead are both capable of forming +2 ions.
Physical
Occurrence
Except for germanium and flerovium, all of these elements are familiar in daily life either
as the pure element or in the form of compounds. However, except for silicon and carbon,
none of these elements are particularly plentiful in the Earth’s crust. Carbon forms a very
large variety of compounds, in both the plant and animal kingdoms. Silicon and silicate
minerals are fundamental components of the Earth’s crust; silica (silicon dioxide) is the
most common constituent of sand.
Tin and lead, although with very low abundances in the crust, are nevertheless common
in everyday life. They occur in highly concentrated mineral deposits, can be obtained
easily in the metallic state from those minerals, and are useful as metals and as alloys in
many applications.
Germanium, on the other hand, forms few characteristic minerals and is most commonly
found only in small concentrations in association with the mineral zinc blende and in coals.
Although germanium is indeed one of the rarer elements, it assumed importance upon
recognition of its properties as a semiconductor.