Physical Properties of Alkaline Earth Metals

Alkaline earth metals are less electropositive than alkali metals. The electropositive character of alkaline earth metals increases down the group. They achieve an inert gas configuration by the loss of two electrons.

Oxidation State

All elements show +2 oxidation state.

Atomic or Ionic Radii

Be < Mg < Ca < Sr < Ba

Size of alkaline earth metals increases from top to bottom due to increase in the number of shells.

Ionization Enthalpy

Be > Mg > Ca > Sr > Ba

As the size increases, it becomes easier to remove an electron from the outermost shell.

Electronegativity

Be > Mg > Ca > Sr > Ba

As the electropositive character increases from top to bottom due to decrease in ionization energy, electronegativity decreases from top to bottom.

Metallic Character

Be < Mg < Ca < Sr < Ba

Metallic character increases as we go down the group due to increase in electropositive character.

Density

Generally density increases from top to bottom as the atomic mass increases.

Melting Point & Boiling Point

They show higher values of melting and boiling points as compared to alkali metals because of the smaller size and stronger metallic bonds.

There is no regular trend down the group. It depends upon packing.

Flame Coloration

Except Be and Mg (due to small size and higher ionization enthalpy), all other alkaline earth metals impart characteristic colors to the Bunsen flame.

• Ca: Brick red
• Sr: Crimson red
• Ba: Sea green