Chemistry

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Atoms and Molecules
“The ‘building bricks’ of elements are called atoms. They are the smallest part of an element that chemically reacts like a bulk sample of the element. If it were possible to take a piece of copper and divide it into smaller and smaller pieces, eventually we would have one atom of copper. Atoms are incredibly small - 35 000 000 copper atoms, laid end to end in a line, would cover the distance of about 1cm. The existence of atoms has been proposed since the time of the early Greeks and it explains the behaviour of substances. The scanning tunnel microscope, developed in 1981, enables us to see atoms.

Two or more atoms can be linked together to form new particles called molecules. The chemical behaviour of the new molecules is different from that of the atoms which make them up. The molecules may be combinations of atoms of the same element. For example, under normal conditions oxygen gas contains diatomic oxygen molecules (two atoms joined together). For this reason, the oxygen molecules is sometimes called ‘dioxygen’.”

This section has been taken from Chapter 2 of Foundations Chemistry by Rob Lewis & Wynne Evans

Using the Earth’s resources

“There are two kinds of resources - renewable resources such as wood and non-renewable resources such as coal or a metal ore.

Renewable resources can be managed by balancing regrowth of the material with its consumption for industry. Non-renewable resources must be conserved to last as long as possible.

The world reserves of non-renewable resources are estimated by geological surveys made on the ground and by pictures and measurements made from satellites. From this information tables are produced which predict how long a non-renewable resource will last if it is used up at its present rate. Many of these predictions show that most of the non-renewable resources will be used up in less than 200 years and some could be used up in your life time.”

This section has been taken from Chapter 17 Mastering Chemistry by Peter Riley.