Here are the list of elements, with their electronic configurations.
|| Atomic No.
|| Electronic Configuration
|| Abundance in Earth's crust (in ppm)
|| [He] 2s2 2p2
|| [Ne] 3s2 3p2
|| 277, 200
|| [Ar] 3d10 4s2 4p2
|| [Kr] 4d10 5s2 5p2
|| [Xe] 5d10 6s2 6p2
configurations of carbon family elements shows that they have four
electrons in their valence shell. Two electrons are in the 's' sub-shell
and the other two, in the 'p' sub-shell. Only Carbon has, in its
penultimate shell S2
configuration. All the other elements have either s2, 2p6 (Si) or s2, p6 , d10 (Ge, Sn, Pb) configurations.
This is the reason why Carbon differs slightly from the other members of its group.
Carbon is the only element of the IV A group,
which occur in nature in the free state. Carbon is present as diamond,
graphite and coal. Carbon also occurs in the combined state, in many
organic compounds such as hydrocarbons, carbohydrates, etc. Carbon is
also present in the atmosphere as Carbon dioxide.
The next element,
Silicon, is the second abundant element after oxygen. It is present in
sand, rocks, etc, in the form of silicates or silica. Germanium is a
rare element. The last two elements are present in the form of its ores. Tin is present as its oxide ore, as Tin Stone, SnO2
. Lead is present as its sulphide ore, Galena, PbS.
is a phenomenon by which an element can exist in more than one form.
Except Lead, Pb, all the other elements of IV A group of this group show
allotropy. These elements exist in different allotropic forms. The different allotropic forms of IV group elements are:1. Carbon
- Crystalline forms - Diamond and Graphite
- Amorphous form - Coal, Coke, charcoal, etc
- Crystalline and amorphous form.
- Amorphous form of silicon is the common form.
Two crystalline forms, called α and β Germanium.4. Tin
- White tin
- Grey tin
- Rhombic tin
Atomic volume, atomic size and ionic size
atomic size and the atomic volume increases as we move down the group,
from carbon to lead. The ionic radii for tetravalent cation increases
steadily from carbon to lead. The increase in size of the ion is due to
the fact that, as we move down the group, an additional shell is being
added to each element. Example: Carbon has 2 shells, while the valence electron of Si enters the 3rd
The density in Carbon family increases as we go down the group.
||3.5 for diamond
2.0 for graphite
The change from
non-metallic to metallic character with the increase in atomic number
is best illustrated by the elements of this group. Carbon and
Silicon, the first two elements, are completely non - metallic. But,
some electrical properties exhibited by Si shows a little bit of
metallic character, thus making it a semi-metal or a metalloid. Germanium exhibits both metallic as well as non-metallic characteristics, thus making it a semi-metal or a metalloid.
The last two elements, tin and lead are distinctly metals.The
reduction in the effective nuclear charge, with the increase in number
of electrons (or the atomic number) and the increase in number of
available orbitals with the increase in size of the atom, is the reason
for increase in the metallic character, as we move down the group.
Carbon family is positioned almost in the middle of the periodic table,
separating the metals from the non metals. The non-metallic
characteristics starts from this family. Thus, carbon family has the metals on their left, and the non- metals on their right. These elements are placed in the p - block of the periodic table.
1. Melting and boiling points
- Carbon, silicon, germanium, tin and lead constitute group 14 elements of the long form of periodic table.
- These are also known as carbon family after the name of the first element of this group.
- They have four electrons in their outermost or valence or the ultimate shell. They constitute a part of representative elements.
In comparison with the group 13 elements, the carbon group elements have much higher melting and boiling points. It is also absorbed that the melting and boiling points show a downward trend as we move down the group, though a little haphazardly.
The decrease is sue to the fact that the inter atomic forces of these molecules decrease as we move down. Carbon and silicon form extraordinarily giant molecules, and thus, have large melting and boiling point.
2. Ionization energy
||Melting point (K)
||Boiling point (K)
Ionization energy decreases from Carbon to lead, though not in a regular order. The irregularity in the decrease of these values is due to the fact that the filling of intervening d- orbitals in Ge and Sn and the f- orbitals in Pb, makes it difficult for them to screen the valence electrons effectively.3. Electronegativity
Carbon is the most electronegative element of the group. There is an irregular decrease in electronegativity as we move down the group. The reason behind this irregularity is because of filling of intervening d and f atomic orbitals.
All the elements of carbon are very useful industrially as well as in our day today life.
1. Valency and oxidation state
- Graphite, an allotrope of carbon, is used in rockets and missile components.
- Silicones are highly stable and non-volatile even on heating. So they find their use in high oil baths and vacuum pumps, etc.
- Silicon is the main component in glass industry.
- Germanium finds its use as a semiconductor material, with silicon.
- Tin and lead finds its use extensively in paint and pigment manufacturing.
Carbon family elements are tetravalent in nature, since they have four electrons in their outermost shell. Since the ionization energy of carbon family elements are very high, M4+
, as expected, hardly exists. On account of their low electronegativity, M4-
also do not exists.
Some of the compounds of carbon, like carbides have carbon exhibiting a valency of C22-
. Silicon does not form tetravalent or divalent cation. The other three elements, Ge, Sn and Pb show both tetra valency and bi valency. Sn2+
and Pb 2+
are more stable and common than Sn4+
.2. Nature of M2+ and M4+ compounds
The nature of compounds of M2+ and M4+ are predicted by Fajan's rule, which states that : Smaller the cation, the greater is the amount of covalent character in its compounds.
ion is smaller than Sn2+
, the compounds of Sn4+
are covalent in nature while those of Sn2+
In lead too, Pb4+
compounds are covalent while that of the 2+ ions are ionic. Thus, in general, M4+
compounds are covalent, while M2+
ions are ionic. As we move down the group, the ionic characteristics of these compounds, increases.
Carbon is a non metal and it forms a lot of covalent compounds.1. Formation of Hydrides
Carbon combines with hydrogen to form CH4
. The hydride formed is covalent in nature.2. Oxides
There are two oxides of carbon, Carbon monoxide and carbon dioxide. Other oxide, C2
also exists.3. Reaction with halides
Carbon reacts with all halides to form a tetra halide - MX4
. This halide is thermally very stable. Tetra halides of Carbon are the only one which is not hydrolyzed by water, due to the absence of 'd' orbital in carbon.
M + X2 → MX44. Formation of acids
Carbon forms both organic and inorganic acids. It forms carbonic acid, H2
, the inorganic acid. There is a whole range of acid, with a chemical formula -COOH formed by carbon. These are studied separately in the name of carboxylic acid under organic chemistry.5. Reaction with alkalies
Carbon does not react with alkalies, though all the other elements in its group are attached by alkalies.
Though many physical properties of carbon have been discussed above, an important physical property of carbon is catenation.
- Catenation is the ability to form compounds in which the atoms are linked to each other in chains or rings.
- Carbon has the greater tendency to combine with other carbon atoms to form quite large carbon chains.
- Carbon also exists in many allotropic forms, both crystalline and allotropic.
- graphite and diamond are two important forms. Also, another form of allotrope, Fullerenes, are studied completely as a new branch of chemistry.
Carbon forms a lot of compounds. Some of them , with their method of preparation are as follows.
1. Percarbonic acids and percarbonates
Carbon forms two percarbonic acids which are
(a) Permonocarbonic acid: These are the salts H2
Examples of such salts are Na2
, K2CO4, etc.
is prepared from the reaction between Na2
and Phosgene, COCl2
2Na2O2 + COCl2 → Na2CO4 + 2NaCl + 1/2O2
(b) Perdicarbonates: These are derived from H2
. These are best represented by potassium and sodium salts whose formula are K2
is prepared by passing F2
in a concentrated solution of Na2
at -13 o
C to -16o
2Na2CO3 + F2 → Na2C2O6 + 2NaF
2. Carbonyl chloride or phosgene
This compound was discovered by John Davy in 1811. It has a chemical formula of COCl2
It is prepared by the direct combination of equal volumes of CO and Cl2
in the presence of bright sunlight.
CO + Cl2 → COCl2
Phosgene is a colorless gas with a penetrating and suffocating odor and is highly poisonous.
3. Carbon disulphide: CS2
This compound was discovered by W. A. Lampadins in 1796. CS2
is manufactured by passing sulfur vapors over hot charcoal or coke.
C + 2S(vapors) → CS2
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- Phosgene is used in dyestuff industry, and in warfare.
- Carbon di-sulfide is used as a solvent for sulfur, white phosphorus, bromine, etc. It is also used in the manufacture of artificial silk and as an insecticide.
- Diamonds, due to their hardness, are used for sawing and cutting marble, cutting glass, etc.
- Graphite is used in the manufacture of electrodes and dry cell batteries.