Alkaline earth metals can be defined as the metals which are present in the group 2 of the periodic table.They
share same chemical properties and there is a gradation in their physical properties.
The group II elements are better known as alkaline Earth metals. These elements have two electrons in their valence
shell and while writing the configuration these notations are preceded by the respective noble gas configurations.
Their general configuration is written as [Noble gas] ns 2 wherein 'n' represents the valence shell.
The electronic configuration of the alkaline earth metals are as follows
Element Symbol Atomic number Electronic Configuration
Beryllium Be
4 [He]2s 2
Magnesium Mg 12 [Ne]3s 2
Calcium Ca 20 [Ar]4s 2
Strontium Sr 38 [Kr]5s 2
Barium Ba 56 [Xe]6s 2
Radium Ra 88 [Rn]7s 2
Given below are some of the alkaline earth metals characteristics :
Atomic and ionic radii
The alkaline Earth metals atomic and ionic radii are smaller compared to members of the alkali metals. As Group II
elements have higher nuclear charge, these allows electrons to be more attracted towards the nucleus resulting in the
reduced size of atomic and ionic radii.
The radii increases while moving down the group due to the gradual increase in the number of the shells and the overall
screening effect.
Physical Property
Be Mg Ca Sr Ba Ra
Atomic Radius (pm) 112 160 197 215 222 --
Ionic Radius (pm)
27 72 100 118 135 148
Melting and Boiling Points
The alkaline Earth metals M.P and B.P ( melting point and boiling point ) are typically low and they do not display the
regular trends down the group. However, melting and boiling points are higher than the corresponding alkali metals of
the same period and this is because alkaline Earth metals have smaller atomic size in comparison. This results in more
closely packed crystal lattices. As they have two electrons in their valence shell resulting in the formation of strong
metallic bonds for atom binding in the metal crystal lattice resulting in higher melting and boiling points.
Physical property Be Mg
Ca
Sr
Ba
Ra
Melting point (k) 560 920 1112 1041 1000 973
Boiling point (k)
2770 1378 1767 1654 2123 1800
19