Organic compounds

The idea

Tetravalency and catenation together give carbon a very large number of compounds; carbon compounds, except carbides, oxides of carbon, and carbonate and hydrogencarbonate salts, are studied under organic chemistry.

Millions of compounds

Chemists know the formulae of millions of carbon compounds. That is many more than the compounds of all the other elements put together.

Which two features of carbon together explain such a large number?

• Tetravalency and catenation
• Hardness and a high melting point
• Forming ions and conducting electricity

Organic or not?

Sort each substance. Most carbon compounds are studied under organic chemistry, but a few groups are the exceptions.

A long list, with a few exceptions

Each carbon atom can hold four partners (tetravalency), and carbon atoms can join into chains and rings (catenation). Together these give a very large number of compounds. A few groups of carbon compounds are left out of organic chemistry.

Tetravalency and catenation together give carbon a very large number of compounds. Carbon compounds, except carbides, oxides of carbon, and carbonate and hydrogencarbonate salts, are studied under organic chemistry.

Notes

Tetravalency and catenation together give carbon a very large number of compounds. Carbon compounds, except carbides, oxides of carbon, and carbonate and hydrogencarbonate salts, are studied under organic chemistry.

Check yourself

Which two features of carbon together give it a very large number of compounds?

Which of these is studied under organic chemistry?

Sodium hydrogencarbonate contains carbon. Why is it left out of organic chemistry?

• Hardness and colour. The book names tetravalency and catenation. Hardness and colour do not explain the number of compounds.
• Tetravalency and catenation — correct. Yes!
• Forming ions and losing electrons. Carbon does not easily gain or lose electrons. The book names tetravalency and catenation.
• Carbon dioxide. Carbon dioxide is an oxide of carbon, one of the exceptions.
• Sodium carbonate. Sodium carbonate is a carbonate salt, one of the exceptions.
• Ethanol — correct. Yes!
• Carbonate and hydrogencarbonate salts are among the exceptions — correct. Yes!
• It does not contain hydrogen. Sodium hydrogencarbonate does contain hydrogen, as its name and formula show. It is left out because hydrogencarbonate salts are exceptions.
• It is made of a single element. It is made of several elements. It is left out because hydrogencarbonate salts are exceptions.