Group 14 (IVA),
The Carbon Group
Valence electron configuration (ns2 , np2)
symbol
carbon
silicon
germanium
tin
lead
electron
configurationn
C
Si
Ge
Sn
Pb
[He]2s22p2
[Ne]3s23p2
[Ar]3d104s2 4p2
[Kr]4d105s2 5p2
[Xe]4f14 5d106s2 6p2
Ionization energy
C
Si
Ge
Sn
Pb
decreases from C to Si
change in an irregular way
(Because of the effect of the filling of
d and f shells)
Oxidation states
Possible oxidation states = +2 , +4
C
Si
Ge
Sn
Pb
Stability of +4 decreases
Stability of +2 increases
Ge (IV) > Ge (II), So Ge(II) is a good reducing agent
Pb(II) > Pb(IV) , Hence, Pb(IV) is a strong oxidizing
agent
Q. 7
Why Pb+4 is considered as a strong oxidizing agent?
Q. 8
What is the hybridization of Si in [SiF6]2- ?
With the aid of suitable diagram, show how the
valence electrons and orbitals of Si involve in the
formation of SiF62-
Carbon
Elemental carbon exists in nature mainly as
the two allotropes
1. diamond
2. graphite
Graphite is used in writing material in pencils,
electrodes, high-temperature devices, and
strong graphite fibers
Diamond is used in jewelry and in drill bits
because it is the hardest substance known
7
diamond
graphite
Catenation
is the ability of a chemical element to form a
long chain-like structure via a series of covalent
bonds.
Catenation occurs most readily in carbon, which
forms covalent bonds with other carbon atoms.
Catenation is the reason for the presence of a
large number of organic compounds in nature.
Internal π bonding using d orbitals
The compounds trimethylamine [(CH3)3N] and
trisilylamine [(SiH3)3N] have a similar kind of formulae,
but have totally different structures.
(CH3)3N
sp3
(SiH3)3N
sp3
sp2
(SiH3)3N
Pπ – dπ overlap
Silica, SiO2
Silica is the basic raw material of the glass,
ceramics, and refractory materials industries
Borosilicate glass, perhaps best known by
the trade name Pyrex®, is extensively used for
laboratory glassware and ovenware
Borosilicate glass is a type of glass with the main
glass-forming constituents silica and boron oxide
12
Structure of Silica, SiO2
EOS
Chapter 21: p-Block Elements
13
Silicate Minerals
Silicate anions, SiO44–, are often quite complex,
but most have as a basic structural unit a
tetrahedron with a Si atom at the center and O
atoms at the four corners
EOS
Chapter 21: p-Block Elements
14
Classification of silicates
In silicate minerals, SiO4 tetrahedra are
arranged in a variety of ways, leading to a
host of mineral forms
1. Ortho silicates
15
2. Pyro silicates
3. Cyclic silicates
general formula:
2n-
(SiO3)n
4. Chain silicates
5. Sheet silicates
Q. 9
Draw the structure of the silicate ion in Ca3(Si3O9)