Oxygen

Atomic Structure
Symbol	O
Atomic Number	8
Atomic Mass	15.99 g/mol
Periodic Table
Group	16
Row / Period	2
Element Category	Nonmetal, Chalcogen
Picture
Liquid oxygen.

Oxygen (O) is a chemical element. In nature, oxygen is a gas with no color or smell. Oxygen is a very important element because it is a part of the air people breathe and the water people drink. Because of this, oxygen supports life. All living things (including humans) need oxygen to live.

History of oxygen

Oxygen was discovered in 1772 by Carl Wilhelm Scheele first, but Joseph Priestley also discovered it two years later and spread the news before Scheele, so many people think that Priestley discovered oxygen first. The word oxygen comes from Greek words: oxus (acid) and gennan (generate).

Oxygen comes to earth from all parts of the universe in meteorites. It is also found in minerals and plants that grow on the earth.

Oxygen in nature

A drop of water.

Water contains oxygen. When one oxygen atom combines with two hydrogen atoms, they form a molecule of water (also written as H₂O). This water is required by all living things to live.

Air also contains oxygen. Air is made of many gases that are mixed together. However, oxygen is especially important because all animals use oxygen to get energy from their food.

Combustion of wood in a match.

Uses of oxygen

Combustion

Oxygen is also what makes burning possible. This is called combustion. When an object or something burns or combusts, oxygen combines with another substance and releases heat and light. For instance, when you burn wood, the oxygen in air combines with the wood to create fire. This ability of oxygen has many uses. But, it also makes pure-oxygen very dangerous. If pure oxygen touches a flame or spark, it can combust and cause great damage.

Combustion is used in many ways. For example, when oxygen is mixed with acetylene, it can create a very hot flame. The hot flame is used in welding, where metal is heated and melted together. Also, oxygen is used to create powerful fuels, which also can be used in rockets and jets.

Production of gas

Pure oxygen can be produced in several ways. In nature, plants produce oxygen by using sunlight, carbon dioxide (another gas) and water. This process is called photosynthesis. Most of the oxygen in the air is produced by photosynthesis.

Oxygen can also be created by humans, using a process called electrolysis. In this process, electricity passes through water. As a result, the water molecules break and release oxygen and hydrogen gas.

Other pages

• Periodic table
• List of common elements