Why does carbon form a large number of compounds? Explain with examples of chains, branches and rings.

1. 1 · Open in one line. Carbon forms millions of compounds because of catenation and tetravalency.
2. 2 · Catenation. Carbon links with carbon to form straight chains (butane), branched chains (isobutane) and rings (cyclohexane, benzene). Carbon-carbon bonds are strong.
3. 3 · Tetravalency. Each carbon forms four bonds with C, H, O, N, S or Cl. Its small size makes these bonds strong.
4. 4 · Draw the shapes. Draw butane as four carbons in a row, isobutane with one branch, and cyclohexane as a ring of six carbons. Add H atoms so that every C has four bonds.
5. 5 · Link to real life. Foods such as starch, proteins and fats, and fuels such as LPG, are all carbon compounds.
6. 6 · Close in one line. So these two properties make carbon unique.

Scoring tip: Name both properties and give an example of each shape. Examiners look for the words catenation and tetravalency.