Understand the Law of Conservation of Mass in Terms of Atoms

Remember those tiny little things called atoms? They make up absolutely everything! So it's no surprise that they play the leading role in all chemical reactions and changes of state!

In both physical changes of state and chemical reactions, mass is conserved and the number of atoms stays the same. Atoms cannot be destroyed. This is known as the Law of Conservation of Mass.

Changes of state are a physical change. But the mass is always conserved, as well as the number of atoms involved. For example, if the mass of an ice cube in solid form was 100 g, then the mass of the water in liquid form would also be 100 g and the mass of the water vapour when it is in gaseous form would also be 100 g. That's because atoms just gain or lose a bit of energy during a change of state and so move around a bit - but the number of them stays the same. 

It's all to do with atoms. When a chemical reaction takes place, atoms in a starting substance rearrange themselves and join back together to form a new substance. In a physical change, atoms rearrange themselves, either getting further apart or closer together. But, the number of atoms will still be the same before and after the reaction. 

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How do you feel about conservation of mass? Is it all coming together now?

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