Introduction

• The alkaline earth metals are less reactive than the alkali metals. • The reactivity of these elements increases on going down the group. • Beryllium and magnesium are kinetically inert to oxygen and water because of the formation of an oxide film on their surface. • However, powdered beryllium burns brilliantly on ignition in air to give BeO and Be3N2. • Magnesium is more electropositive and burns with dazzling brilliance in air to give MgO and Mg3N2. • Calcium, strontium and barium are readily attacked by air to form the oxide and nitride. • They also react with water with increasing vigour even in cold to form hydroxides. • All the alkaline earth metals combine with halogen at elevated temperatures forming their halides. • (NH4)2BeF4 is the best route for the preparation of BeF2, and BeCl2 is conveniently made from the oxide. • BeO + C + Cl2 à BeCl2 + CO • All the elements except beryllium combine with hydrogen upon heating to form their hydrides, MH2. • BeH2, however, can be prepared by the reaction of BeCl2 with LiAlH4.

Pre-Requisites:

Alkali earth metals, elements, periodic table, chemical properties

Activity:

Bones and teeth have calcium in them.

Real Life Question:

Where do you find calcium in the body..?

Key Words / FlashCards

Learning aids / Gadgets

Real life uses :

Calcium is important for the bone and teeth development.

Places to visit :

Kitchen.

Practical examples around us

What you learn in Theory:

• The alkaline earth metals are less reactive than the alkali metals. • The reactivity of these elements increases on going down the group. • Beryllium and magnesium are kinetically inert to oxygen and water because of the formation of an oxide film on their surface. • However, powdered beryllium burns brilliantly on ignition in air to give BeO and Be3N2. • Magnesium is more electropositive and burns with dazzling brilliance in air to give MgO and Mg3N2. • Calcium, strontium and barium are readily attacked by air to form the oxide and nitride. • They also react with water with increasing vigour even in cold to form hydroxides. • All the alkaline earth metals combine with halogen at elevated temperatures forming their halides. • (NH4)2BeF4 is the best route for the preparation of BeF2, and BeCl2 is conveniently made from the oxide. • BeO + C + Cl2 à BeCl2 + CO • All the elements except beryllium combine with hydrogen upon heating to form their hydrides, MH2. • BeH2, however, can be prepared by the reaction of BeCl2 with LiAlH4.

What you learn in Practice:

• Important ions for the body like calcium and magnesium belong to group 2 in the periodic table.