Chemistry

Chemistry is the science of matter: what everything around us is made of, and how it changes. Every object you can touch is built from tiny particles called atoms, which join together in different combinations to make all the substances in the world: from water and air to plastics, food, fuel and the materials of your own body. Chemists study what these substances are made of, how they react with each other, and how to make new ones to solve real-world problems. Chemistry sits between physics (which studies the basic rules of matter and energy) and biology (which studies living things).

• Known elements118Listed in the periodic table
• Naturally occurring elements94The rest are made in labs
• Most abundant elementHydrogenRoughly 75% of all atoms in the universe
• Most abundant in Earth's crustOxygenApproximately 46% by weight
• Known compoundsOver 200 millionAnd growing daily
• Three main branchesOrganic, inorganic, physical

The main branches of chemistry

Chemistry is so big that most chemists specialise in just one part of it.

• Organic chemistry: the chemistry of carbon-based compounds. Despite the name, it covers more than just living things: plastics, fuels, medicines and many everyday materials are organic.
• Inorganic chemistry: the chemistry of everything else: metals, minerals, gases, salts.
• Physical chemistry: how chemicals behave under different conditions of energy, pressure and temperature. Bridges chemistry and physics.
• Biochemistry: the chemistry of living things. How food is digested, how cells make energy, how DNA copies itself.
• Analytical chemistry: figuring out what a substance is made of. Used in forensic science, food testing, medicine and pollution monitoring.

What chemists do

Chemists work on some of the most important problems in modern life:

• Designing new medicines to treat diseases.
• Creating new materials: stronger metals, better plastics, more efficient batteries.
• Producing clean energy: solar cells, fuel cells, lithium batteries.
• Growing more food through fertilisers and crop protection.
• Cleaning up pollution and protecting the environment.
• Understanding the basic rules of how the universe works at an atomic level.

Fact Almost everything around you is made from just a handful of common elements. Your body is 99% hydrogen, oxygen, carbon, nitrogen, calcium and phosphorus. The air is mostly nitrogen and oxygen. The Earth's crust is mostly oxygen, silicon, aluminium and iron. The same few atoms, in different arrangements, make up the rocks under your feet, the water in your glass, the food in your fridge and the cells of your body.

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