This document discusses the properties of alkaline earth metals, specifically beryllium, magnesium, calcium, strontium, and barium. It covers their occurrence in nature, physical properties like melting points and flame tests, and similarities between beryllium and magnesium, including their tendency to form covalent compounds and hydrides.

1. D. Jim Livingston
Asst. Prof. of Chemistry
St. John’s College.

2. The Alkaline Earth Metals
IIA [ns2] group elements are called alkaline earth
metals.
Mg -second most abundant metallic element in the sea,
and carnallite (KCl.MgCl2.6H2O) in earth crust.
Ca- occurs as calcium carbonate (marble, chalk etc) and
with magnesium as dolomite (CaCO3.MgCO3).
Sr and Ba - rare and are found as carbonates and
sulphates.
Be- rare and is found as beryl (Be3Al2(SiO3)6).
Occurrence

3. Physical properties

4. Flame Test :
Size of Be and Mg is very small and their electrons are
strongly bonded to the nucleus. These
electrons cannot be excited to higher energy level by the
flame of the burner. Thus, Be and Mg do not impart any
colour to the flame.
Solubility in Liquefied Ammonia :
Ca, Sr and Ba give ammoniated electron by getting
dissolved in liquefied ammonia due to large size, due to
which the solution turns blue.
Ca + nNH3 Ca+2 + 2e– (NH3)n
Melting point and Boiling Point :
The melting and boiling points are higher as compared to
metals of IA group.
Hardness decreases from Be to Ba, due to which melting
and boiling points decrease.
Be > Ca > Sr > Ba > Mg
Be - hcp at room temperature, bcc at melt.
Mg - hcp at room temperature, hcp at melt.
Ca - fcc at room temperature, bcc at melt.

5. Sr + O2 SrO2

9. Basic Beryllium Acetate

10. Both metals have the tendency to form covalent
compounds
Both metals dissolves in alkalies to form soluble
complexes beryllates and aluminates
The oxides of both are hard, high melting insoluble
solids
The oxides and hydroxides of both are amphoteric
In nature
Carbides of both the metals react with water
Liberating methane gas
Diagonal Relationship
between Be and Mg

11. Both Be and Al form polymeric covalent hydrides
while hydrides of other alkaline earth are ionic.
BeCl2 and AlCl3 both have a bridged polymeric
structure.
Be and Al both form fluoro complex ions [BeF4]2-
and [AlF6]3- in solution state whereas other
members of 2nd group do not form such
complexes.
Both forms hydrated ions in aqueous solution