What are the characteristics of the alkaline earth metals?

Aug 26, 2022, 16:45 IST

General characteristics of alkaline earth metals:

1. Electronic configuration: ns²

Element	Atomic Number	Electronic configuration
Be	4	[He]2s²
Mg	12	[Ne]3s²
Ca	20	[Ar]4s²
Sr	38	[Kr]5s²
Ba	56	[Xe]6s²
Ra	88	[Rn]7s²

(Ra^* is a radio active element)

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2) Atomic and ionic radii:

• The atomic and ionic radii of alkaline earth metals, are quite large, but smaller than those of alkali metals, due to increased nuclear charge of these elements which tends to draw the orbital of electrons, inward.

• On going down the group, the atomic as well as ionic radii increase, due to the gradual addition of new shell at each step and also because of screening effect. Trends are :

Atomic, Ionic radii, alkalimetals > alkaline erathmetals (Å)

Be < Mg < Ca < Sr < Ba < Ra

0.9 1.33 1.74 1.91 1.98 -

Be²⁺ < Mg²⁺ < Ca²⁺ < Sr²⁺ < Ba²⁺ < Ra²⁺

0.31 0.685 0.99 1.13 1.35 -