Key points
Nitrogen is an elementA pure substance which is made from only one type of atom. Elements are listed on the periodic table.. It's a gasOne of the three states of matter. Gases, like oxygen or helium, do not have a fixed shape and can expand to fill their container. 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.
What is nitrogen?
How is nitrogen used?
Nitrogen has just one type of atomThe smallest particle of an element. We often think of atoms as tiny spheres, but in fact they are made from smaller particles called protons, neutrons and electrons., so it is an element. It's found naturally as a moleculeTwo or more atoms which are strongly bonded together. The smallest particle of a substance that has all of the physical and chemical properties of that substance., each containing two nitrogen atoms. This gives it a chemical formula of 狈鈧. Nitrogen has a low melting pointThe highest temperature at which a substance can exist as a solid. For solid water (ice), the melting point is 0 掳C. and boiling pointThe highest temperature at which a substance can exist as a liquid. Evaporation happens rapidly when a liquid reaches boiling point. and is a gas at room temperature.
The Earth鈥檚 atmosphereThe atmosphere is the layer of gases surrounding a planet. 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 鈭196 掳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.
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