Physical Properties of Group 14 Elements
This group consists of carbon, silicon, germanium, tin, and lead. The outer electronic configuration of the elements of this group is ns2 np2 whereas n is variable and it varies from 2 to 6. The elements of this group exhibit the covalent oxidation state of +4.
Carbon is the first element of this group and is different from the other members due to its high electronegativity, absence of d orbitals and small size. The group is starting from the element that is non-metal and the last elements are non-metals. The metallic character increases in descending the group.
The first element is non-metal, silicon is the metalloid and germanium is the non-metal but it possesses some of the metallic characteristics, whereas tin and lead are the metals.
The covalent and ionic radius is increased by moving down the group. There is a small difference between the silicon and germanium and it is due to the intervening 3d electrons in the germanium which is responsible for shielding the less effective nuclear charge. Similarly, there is a small difference in the size of lead and tin and it could be explained based on the intervening of 4f electrons.
By moving down the group the melting and boiling points are decreased but there is an exception for the lead as it’s melting point is slightly higher than that of the tin. Silicon and germanium also have high melting points as they have the diamond type crystal lattice. The decrease in the melting point from top to bottom of the group is due to the increase of the covalent radii and weakening of the M-M bonding.
Chemical Properties of Group 14 Elements
The reactivity of the elements in group 14 decreases down the group. It happens that the inner pair effect is becoming increasingly effectively by moving down the group. The stability of the state of +4 is decreased whereas the +2 oxidation state is increased on moving down the group.
Carbon, silicon, and germanium are not affected by water and diluted acids. Tin upon reaction with the steam gives hydrogen and tin oxide. Lead is also unaffected by the water as a protective oxide layer is formed at the surface. Tin and lead can react with the diluted nitric acids.
Alkalis do not affect carbon. Silicon reacts with the alkalis and forms the silicates. Tin and lead on reaction with the alkalis form the stannate and plumbate. Tin and lead are amphoteric in nature and their reaction with the alkalis proves this nature. At higher temperatures, graphite reacts with the Florine and gives (CF)n. Silicon and germanium react with all of the halogens and form the volatile compounds. Tin and lead are the less reactive elements but they can react with the halogens.
Depending on the chemical properties these elements have various uses. Carbon is an important and basic element of life and it is present in all the living materials. Silicon has the properties of semiconductor and it is commonly used in the solar cells and computer chips. Lead is used to block the radiation. Tin is unreactive so it is used to make the cans.
