1. Peculiar Behavior Of Beryllium (Be) Anomalous Behaviour of Beryllium (Be) [differences of Be from its family Members]

2. Anomalous Behavior of Beryllium ■Be show different behavior than its family members. ■It is due to following reasons. ■Size of Be is very small. ■Electronegativity of Be is quite high than its family members. ■Exceptionally small atomic and ionic size of Be ■High ionization energy. ■Absence of d-orbitals in its valence shell. ■Some important properties in which beryllium differ from the rest of the members of its groups are as follows.

3. Differences ■Be is as hard as iron. ■It is quite hard to scratch glass, while other alkaline earth metals are softer than Be but still harder than alkali metals. ■Alkaline earth metals (ns2) are denser than alkali metals (ns1) ■Because metallic bonding in alkaline earth metals is stronger than alkali metals ■Due to presence of two electrons in valence shell as compared to one electron in alkali metals

4. Melting and Boiling Point of Be ■Melting and boiling point of Be is higher than other alkaline earth metals. ■Alkaline earth metals have higher melting points than alkali metals. ■They have two electrons in their valence shell resulting in the formation of strong metallic bonds for atom binding in the metal crystal lattice. ■In principle all group IIA metals can reduce water. ■But Be from insoluble oxide coating over the surface that protects it from further attack. ■Be is more resistant to complete oxidation as compared to its family members, because of BeO coating.

5. Reaction with Alkalis ■Only Be react with alkalies to give H 2 gas while other alkaline earth metals don’t give this reaction. ■Be + NaOH → Na 2 BeO 2 + H 2 ■Beryllium form covalent compound whereas other member form ionic compound. ■Because of covalent character, salt of Be are easily hydrolyzed ■Be oxide and hydroxide are amphoteric whereas oxides and hydroxide of other alkaline earth metals are basic in nature. ■BeO + HCl → BeCl 2 + H 2 O ■BeO + NaOH → Na 2 BeO 2 + H 2 O

6. Reaction with Carbon ■Carbide of Be are covalent in nature while carbide of other alkaline earth metals are ionic in nature ■Beryllium carbide (Be 2 C) reaction with water to give methane gas while carbide of other members form acetylene gas. ■Be 2 C + 4H 2 O → 2Be(OH) 2 + CH4 ■Ca 2 C + 4H 2 O → 2Ca(OH) 2 + C 2 H 2 (HC≡CH)