Chapter 4 — Carbon and its Compounds
Fuels, plastics, medicines, soaps, vinegar, the sugar in your tea and the cells of your body: carbon forms more compounds than all the other elements put together. Find out why — covalent bonds, chains and functional groups — and how a few reactions explain it all.
Pick up anything near you. The paper of this page, the ink, your pen, your cotton or polyester clothes, the LPG that cooks your food, the petrol in the vehicles outside, the medicine in a first-aid box, the vinegar in the kitchen, the soap at the wash-basin — and the person reading this. All are built from carbon compounds. Chemists have identified more than ten million of them, many more than the compounds of every other element together, although carbon makes up only a tiny share of the Earth's crust. Carbon is also the element of life: every protein, every fat, every carbohydrate and the DNA in your cells is a carbon compound.
This chapter explains the secret of carbon's variety. Carbon neither gives nor takes electrons: it shares them, forming four strong covalent bonds, and it bonds to itself to make chains, branches and rings. You will meet the diamond, graphite and fullerene forms of the pure element; learn how the carbon compounds are grouped into homologous series by their functional groups and named by the IUPAC rules; study how they burn, oxidise, add hydrogen and substitute chlorine; and finally look closely at ethanol, ethanoic acid, sweet-smelling esters and the soaps and detergents that clean through micelles.
- explain why carbon forms covalent bonds, and draw electron-dot structures of $\mathrm{H_{2}}$, $\mathrm{O_{2}}$, $\mathrm{N_{2}}$, $\mathrm{H_{2}O}$, $\mathrm{CH_{4}}$ and $\mathrm{CO_{2}}$ with single, double and triple bonds;
- describe the properties of covalent compounds and the structure and properties of diamond, graphite and fullerene $\mathrm{C_{60}}$;
- use catenation and tetravalency to explain the variety of carbon compounds, and distinguish saturated and unsaturated compounds, chains, branches, rings and isomers;
- identify the functional groups halo, $-\mathrm{OH}$, $-\mathrm{CHO}$, $>\mathrm{C{=}O}$, $-\mathrm{COOH}$, C=C and C≡C, define a homologous series and name compounds of up to six carbons by the IUPAC rules;
- write balanced equations, with conditions, for combustion, oxidation of ethanol, hydrogenation and the chlorination of methane, and explain clean and sooty flames;
- describe the preparation, properties and uses of ethanol and ethanoic acid, esterification and saponification, and explain how soaps and detergents clean and why soap fails in hard water.
Sections in this chapter
Bonding in Carbon: the Covalent Bond
Why carbon shares electrons; electron-dot structures and multiple bonds; properties of covalent compounds; diamond, graphite and fullerene.
Versatile Carbon: Homologous Series and Nomenclature
Catenation and tetravalency; chains, branches, rings and isomers; functional groups; homologous series; IUPAC names.
Chemical Properties of Carbon Compounds
Combustion and sooty flames; oxidation of ethanol; addition and hydrogenation; substitution in sunlight.
Ethanol, Ethanoic Acid, Soaps and Detergents
Reactions of ethanol and ethanoic acid; esters and saponification; micelles, hard water and detergents.