What is nitrogen?
Nitrogen is an element. It's a gas at room temperature.
Nitrogen makes up about 78% of the Earth's atmosphere.
Liquid nitrogen is very cold, so it is often used to freeze food.
How is nitrogen used?
Nitrogen has just one type of atom, so it is an element. It's found naturally as a molecule, each containing two nitrogen atoms. This gives it a chemical formula of N₂. Nitrogen has a low melting and boiling point and is a gas at room temperature.
The Earth’s atmosphere is made up of 78% nitrogen. The next most common gas is oxygen, at 21%. Nitrogen isn't very reactive, but it can react with oxygen at high temperatures, such as in car engines. These reactions make nitrogen oxides.
The boiling point of nitrogen is −196 °C, so liquid nitrogen is very cold indeed. This means liquid nitrogen is ideal for freezing food, such as vegetables, very quickly, allowing them to stay fresher for longer.