Very small quantities of carbon are found in the earth’s crust as the free element. It is present in approximately one million known compounds. One of the unique properties of carbon is that its atoms combine with each other to form long ring compounds.
Allotropic Forms of Carbon:
Carbon exists in three different forms having different physical properties. When an element is found in more than one physical form in the same state, it is called allotropy and such physical forms are called allotropic forms. Diamond, graphite and Bucky balls are the allotropic forms of carbon. These allotropic forms have different physical properties such as appearance and density but they are the same element and have the same chemical properties.
It is a colorless, transparent and crystalline form of carbon which is found in the earth under great heat and pressure. It is one of the hardest substance known, hence is used for tipping rock drills, in glass cutting, in polishing other precious stones.
It is a second crystalline form of carbon found in nature or made from coal by heating k in electric furnace. It is a soft black solid which has shiny and a greasy feeling. It is used for the core of “lead pencils”, as a lubricant and in paints.
One of the use of this is If a key is stiff in a lock, rub the end of the key with a soft pencil. This contains lots of graphite which will lubricate the movement of the key and hopefully, make the lock easier to open.
(iii) Bucky Balls:
Bucky balls are the third form of pure carbon known to exist naturally. It is used as a semi-conductor, conductors and lubricants.
The Non-Allotropic Forms of Carbon
Charcoal and soot are also forms of carbon but they do not occur naturally. They are made by heating animal bones, wood, nut shell, sugar, blood or coal in a limited amount of air. Coke is another form of carbon which is made by heating coal at about 1300°C in the absence of air. Charcoal is used for absorbing dangerous gases. It is also used by the artists. Coke is used as a fuel and as a reducing agent in various chemical industries.
Organic chemistry is the chemistry of compounds which contain the element carbon.
Most of these compounds also contain hydrogen and many also contain oxygen or other element. There are a few compounds which contain carbon but are not classified as organic compounds. Carbon monoxide, carbon dioxide and the metal carbonates axe examples.
Types of Carbon Compounds
Carbon occurs in large number of naturally occurring compounds e.g. natural gas (methane) and many of our fuels are compounds of carbon and hydrogen. Coal is a mixture of compound containing carbon, hydrogen and oxygen. There are many in inorganic carbon compounds such as carbonates of sodium, calcium, and magnesium.Carbon is also present in our food and every part of our body. All plant life is made up of compounds containing, carbon, hydrogen and oxygen. In the atmosphere it is present in the form of carbon dioxide.
Hydrocarbons are the simplest organic compounds. The molecules of hydrocarbons are made up of only two elements hydrogen and carbon. They occur naturally in fossil fuels, petroleum, coal and peat. The important class of naturally occurring organic compound is carbohydrates. The simplest form of carbohydrates is glucose. Other than carbohydrates proteins, fats and oils are also very important organic compounds. The flesh of human beings, animals, birds and fishes are made of proteins. Many of the organic compounds are made by man. They are artificial fibres, plastics, medicines, paints and many other things.