Ions always have the same electronic structure as elements in which group of the periodic table?

In 0 group of the periodic table

Explanation:

So they will not react with other atoms because they have a full outer shell of electrons and an overall charge of 0.

Hope it helps.

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.