Chemicals everywhere
Everything you can breathe, see, ingest or touch is made up of chemicals. All matter, including us, is made of chemicals. Chemistry is the study of the composition, structure, properties and reactions of matter.
Everything is made of chemicals
Everything is made of chemicals. This includes the whole Earth – all matter in it and on it is made of chemicals.
Matter
Matter is everything around you – whether it’s solid, liquid or gas. Matter is made of tiny particles called atoms. Atoms are like individual LEGO blocks. They are the smallest unit that anything can be broken down into without doing something extreme (like taking a blowtorch to a LEGO block or smashing atoms in a nuclear reactor). These atoms, like LEGO blocks, can be bonded together in different ways to form a variety of structures. Matter has mass and volume.
Chemicals
Matter (anything made of atoms) can also be called a chemical. So if atoms are LEGO blocks, chemicals are the structures you can build with them. They can be in any form – liquid, solid or gas. Chemicals can be a pure substance or a mixture. For example, water (H2O) is a chemical. It’s a pure chemical because it is homogeneous – pure water is the same throughout its structure. It is made up of the same molecules (H2O), each having the same combination and structure of atoms – the same ratio of hydrogen to oxygen, bonded in the same way. Other commonly found chemical substances in pure form are diamond (carbongold, table salt (sodium chloride) and refined sugar (sucrose).
We may think that a chemical substance is pure when in fact it is a combination of chemicals. For example, water may contain small amounts of dissolved sodium chloride and compounds containing iron, calcium and many other chemical substances.
Elements
An element is a chemical substance that is made up of only one type of atom. It cannot be broken down or transformed into a different element (though it may be transmutated into another element through a nuclear reaction). The elements are represented in the periodic table of elements.
Periodic table of elements
The elements are represented in the periodic table of the elements. The 4 groups in this table (S, P, F and D) are essentially based on each element's electron behaviour and orbit.
As of November 2016, there are 118 known elements. Each is represented by a chemical symbol. Most elements are metals – for example, gold (Au), silver (Ag) and iron (Fe) – and others are non-metals, for example carbon (C), nitrogen (N) and oxygen (O).
Chemical compounds
A chemical compound is a pure substance made up of two distinct elements chemically combined. An example of a chemical compound is water (H2O). It is formed by chemically combining the elements hydrogen (H) and oxygen (O).
Water molecule
Water molecules contain two hydrogen atoms (pictured in green) bonded to one oxygen atom (blue). The large oxygen atom has a stronger attraction for electrons than the small hydrogen atoms. Because the oxygen atom has a stronger pull on the negative bonding electrons the oxygen atom has a slightly negative charge and hydrogen atom a positive charge. This unequal sharing of electrons is called a polar bond or dipole. This causes the hydrogen atoms in one water molecule to be attracted to the oxygen atom in another water molecule. This attraction is known as hydrogen bonding. Water can change from a liquid to a solid or a gas and back to a liquid, but its molecular structure always stays the same.
Mixtures
Often, elements and compounds are found in mixtures. A mixture is a combination of two or more substances in which each substance retains its identity. Generally, they can be separated out into the component substances. Soil and air are common examples of mixtures.
Naming chemicals
Every chemical substance has one or more systematic name, usually named according to rules set out by the International Union of Pure and Applied Chemistry (IUPAC). This federation represents chemists in individual countries. It is important that all countries recognise a chemical by the same name.
Many compounds are also known by their more common, simpler names, many of which pre-date the systematic name. For example, glucose (sugar) is now systematically named 6-(hydroxymethyl)oxane-2,3,4,5-tetrol.
Manufactured verses natural chemicals
Manufactured chemicals are ones that have been made by people. They are often called synthetic chemicals. Natural chemicals are ones that are found in nature (produced by plants and animals). Some people think there is a fundamental difference between manufactured chemicals and natural ones. Actually, if a chemical is found in nature and the same chemical is manufactured, there is no difference between them. For example, vitamin C from fruit is exactly the same as synthetically made vitamin C.
Vitamin C
Vitamin C from oranges is exactly the same as synthetically made vitamin C.
Some people also think that manufactured chemicals are bad while natural chemicals are good. This also is a fallacy. Many toxic chemicals are found in nature – in fact, some of the most deadly compounds are found in nature.
