A + ion (positive ion, one with extra positive charge)?

If an ion has a positive charge then it has lost an electrons.

Explanation:

So you don't "gain" anything when the ion has a positive charge. It loses an electron which means it has more protons than electrons. Thus, the ion has a positive charge. If it "gained" an electron then it would have a negative charge.

catya your not at all which answer i've seen you do this on another question!

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.