What is the charge on the strontium ion?

Here is a quick answere: The charge of a strontium ion is +2. The charge of an ion is determined by the amount of electrons compared to the number of protons, so a charge of +2 indicates that the ion has two more protons than electrons.

You use the atomic number to find out how many protons and neutrons there are in the atom. you use the atomic mass to find out how many protons and electrons there are in the atom. 

False, as a substance changes from a solid to a liquid and from a liquid to a gas the molecules get farther apart from each other