Question

atomic no. of magnesium ion

Answer 1

atomic mass of magnesium is 12 u + 12 u = 24 u. Number of neutrons = Mass number– Atomic number= 27-13 = 14. Thus, phosphideion has same number of protons and neutrons as phosphorus atom but has three electrons more. Mg2+ ion is formed by loss of two electrons byMg atom.

Answer 2

Magnesium's electronic configuration=2, 8,2.
so atomic no. is 12 and valency is 2.