Atoms of different elements usually have different mass numbers, but they can be the same. For example, the mass number of argon atoms and calcium atoms can both be 40. The atomic number of a ...

The mass of one substance in a reaction can be calculated if the masses of the other substances are known. For example: copper carbonate decomposes on heating to make solid copper oxide ...

Sometimes a noun looks like it should be plural when it isn’t. Chances are that this noun is called a mass noun. Mass nouns are nouns that, by their very nature, are plural. These are also called ...