What is the charge on a magnesium ion? how do they get that charge?

A) Magnesium is in group 2. That means it has two electrons in its outer shell when these are lost, a magnesium ion is formed Mg2+ is formed. 

b) A magnesium ion get its charge because it has the two electrons in the outer electron shell of a magnesium shell. Both are lost when it changes to an ion leaving it with 12 positively charged protons and 10 negatively charged electrons. This produces a +2 positive charge.

Ethene molecular fórmula= c2h4molecular weight = 29.046g/molhope it : )