Physical properties of group 2 metals

Electronic configurations All the alkaline earth metals have two electrons in their outer shell; Be = 1s2 2s2 Mg = 1s2 2s2 2p6 3s2 Ca = 1s2 2s2 2p6 3s2 3p6 4s2 Ba = 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2

Atomic size The radius increases down the group as an extra shell of electrons is added. Element Metallic radius (nm) Mg0.16 Ca0.197 Sr0.215 Ba0.224

First ionisation energy The first ionisation energy is that needed to form one mole of singly charged ions from a mole of gaseous atoms. Element First ionisation energy Mg736 Ca590 Sr548 Ba502

Upon reacting the M 2+ ion is formed. The energy required to form this ion decreases as the group is descended. Reactivity therefore increases down the group. IE 1 Kj/mol IE 2 Kj/mol Sum Kj/mol Mg Ca Sr Ba

Melting point Group 2 elements are metals with relatively high melting points. MPs generally decrease down the group as the delocalised electrons are further from the nuclei, hence the metallic bonding is weaker. Mg is an exception as it has a different type of lattice which makes its particles easier to separate. Element Melting point (K) Mg922 Ca1112 Sr1042 Ba998