Occurance of non-metals

OCCURANCE OF NON-METALS

HYDROGEN:

Hydrogen is the most abundant element in the universe. It is the chief element that makes up the sun and other stars. On earth, hydrogen, mainly occurs in combined form as a constituent of water (about 11% by weight of water is hydrogen), petroleum, natural gas, coal, clay, and all animals and plants.

NITROGEN:

Nitrogen mainly occurs in the free state in the atmosphere. About 76% by mass of air is nitrogen. In the combined state, it is a constituent of minerals such as Chile saltpeter (NaNO3) and nitre (KNO3).

OXYGEN:

Oxygen is the most abundant element in the earth's crust. It occurs in the free state in the atmosphere, forming about 23% by mass of the atmosphere. In the combined state, it constitutes about 80% by mass of water. It is also present in the combined state in the earth's crust as oxides, carbonates and silicates of metals.

CARBON:

In the free state, carbon occurs as graphite, diamond and coal. Diamond and graphite are pure forms of carbon. Coal contains 60-90% of carbon. In the combined state it occurs in the atmosphere as carbon dioxide. In the earth's crust, it occurs as carbonates of metals and as fossil fuels. Carbon is the central element of all living matter.

SILICON:

Silicon is the second most abundant element in the earth's crust. It does not occur in the free state. In the combined state, it occurs as silica (SiO2) and silicates. The most common form of silica is sand.

SULPHUR:

Sulphur occurs in the free state in the earth's crust. In the combined state, it occurs in rocks as metal sulphates and sulphides. It also occurs as hydrogen sulphide (H2S) which is present in petroleum and natural gas.

Noble gases such as helium, neon, argon, krypton and xenon occur in elemental form in air. 

Extraction of non-metals from their sources is equally important. Non-metals so obtained help in the production of many useful chemicals.