*The Group 2 elements are all metals with a shiny, silvery-white colour.
*harder and denser than sodium and potassium
*higher melting points than sodium and potassium
*Atomic and ionic radii increase as you move down the Group
*Three of these elements give characteristic colours when heated in a flame:
Mg brilliant white
Ba apple green
|magnesium burning in nitrous oxide
Magnesium is the only Group 2 element used frequently. It is used in flares, tracer bullets and incendiary bombs because
of the bright light it gives off when it burns. It is also used to create an alloy with aluminium to produce a low-density,
strong material used in aircraft production. The oxide that magnesium forms has such a high melting point that it is used
to line the inside of furnaces.
*All Group 2a metals can be found in the earth's crust, but not in their pure form. This occurs because of the high reactivity
of this group.
*Magnesium is the eighth most abundant element in the Earth’s crust, and calcium is the fifth.
*The main source of magnesium is the ocean. Magnesium is pulled from ocean water by adding calcium hydroxide. The resulting
reaction precipitates magnesium hydroxide.
Group 2a elements are called Alkaline Earth Metals because of the basicity of their oxides. The only
oxide to show acidic properties such as disolving in aqueous solutions is BeO.
The more active of the Alkaline Earth Metals react with water just like the Alkali Earth metals do. This reaction
produces hydrogen gas. Calcium, strontium and barium perform this reaction at 25 degrees C. Magnesium and barium
do not react with water at 25 degrees C. Magnesium reacts with boiling water.
The heavier alkaline earth metals react with nitrogen or hydrogen at high temperatures to produce ionic nitride
or hydride salts. Barium hydride cannot be formed by a combination of barium and hydrogen, but by a double displacement
involving barium chloride and lithium hydride.