Page 4 - Curriculum Visions Dynamic Book

Introduction
An element is a substance that cannot be broken down into a simpler substance by any known means. Each of the 92 naturally occurring elements is therefore one of the fundamental materials from which everything in the
Universe is made.
Nitrogen
Nitrogen, chemical symbol N, is a colourless, relatively unreactive (inert) gas without any
smell. It is a kind of inert “filler” in our atmosphere, making up over three-quarters of the air
we breathe.
The word nitrogen is made up from two
Greek words: nitron, meaning saltpetre, and genes, meaning producing. This is because the most important historic use of nitrogen was as saltpetre, a compound called potassium nitrate, well known since ancient times as a fertiliser.
Nitrogen as a gas is relatively inert, but some nitrogen is also vital to life as part of amino acids, the building blocks of proteins. Thus, all living things are made up of compounds including nitrogen, oxygen, hydrogen and carbon. Each of these comes from the air and water around us.
Nitrogen from the air cannot be used directly by plants, so they rely on getting it from soluble nitrogen compounds instead.
Each molecule of nitrogen is made up of
two nitrogen atoms linked together extremely strongly. Energy is needed to convert the nitrogen (N2) molecules in the air into nitrogen-containing compounds. The process of converting the
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