Discuss the general characteristics and gradation in properties of alkaline earth metals.
General properties of alkaline earth metals are as follow:
Physical Properties:
1) As we go down the group, atomic size increases due to addition of new shells.
2) These metals lose two electrons to acquire noble gas configuration. Therefore, their oxidation state is +2.
3) alkaline earth metals have large size, their ionization enthalpies are found to be fairly low. However, their first ionization enthalpies are higher than the corresponding group 1 metals.
4) As we go down the group, ionisation energy decreases, as it is easy to take out electrons now from shells.
5) Ca, Sr, and Ba impart characteristic colours to flames.
Ca – Brick red
Sr – Crimson red
Ba – Apple green
Chemical properties:
1) Alkaline earth metals react with halogens at high temperatures to form halides.
M +X2→ MX2
2) All the alkaline earth metals, except Be, react with hydrogen to form hydrides.
3) They react readily with acids to form salts and liberate hydrogen gas.
M + HCl → MCl2 + H2