Alkaline Earth MetalsBeryllium

Magnesium

Calcium

Strontium

Barium

Radium

• Why were these elements called “alkaline earth

metals”?

• What do you think about the uses of these elements

commonly?

Alkaline Earth Metals

• The word “earth” was used for the oxides of group 2A by the

ancient scientists.

• Alkaline earth metals, after the alkali metals, are secondary

metals with strong metallic properties.

• The group 2A elements are less active than those of 1A, but

more active than those of group 3A.

• Except Be, all form ionic compounds.

• Be forms mostly covalent compounds.

• The atomic radius increases from top to bottom.

•The melting point, boiling point and the hardness of the elements decrease from top to bottom.

• Beryllium is the hardest alkaline earth metal

• Barium is the softest alkaline earth metal.

• Malleable and ductile.

• Excess Mg+2 and Ca+2 in water means that it is hard.

Characteristic Flame Colors of Alkaline Earth Metals

BariumCalcium StrontiumMagnesium

Minerals of Some Alkaline Earth Metals

Chemical Properties

• They are Covered by their oxides when they are exposed to

air.

• Burn in air with bright flame.

•Activity of the metals increases from Be to Ba.

• Reactions of Ca, Sr and Ba are easy with water.

• Reactions of Be and Mg with water are difficult.

Chemical Properties

• Ca (s) + 2H2O(l) → Ca+2(aq) + 2OH-(aq) + H2(g)

• Mg (s) + 2H2O(l) → Mg(OH)2(s) + H2(g)

• 2Mg (s) + O2(g) → 2MgO(s)

• Mg (s) + H2(g) → MgH2(s)

• Ca (s) + 2HCI(aq) → CaCl2 + H2(g)

• Be (s) + 2HCI(aq) → BeCI2 + H2(g)

• All oxides and hydroxides of alkaline earth metals show basic properties.

• Oxides and its hydroxides of beryllium show amphoteric properties.

Compounds

• Ionic

• Have high melting and boiling points.

• Thermally stable.

• Less soluble in water than those of 1A metals.

• Solubility of salts increase from Be to Ba.

• Obtained by heating calcium

carbonate (limestone) at 900°C.

• CaCO3(s) → CaO(s) + CO2(g)

Calcium Oxide, CaO

Calcium Carbonate, CaCO3

• It forms by evolving CO2 gas from Ca(OH)2 solution.

• Small gray solid pieces

• Used widely in industry

• Prepared by the reaction of calcium oxide (lime) and coke.

CaO(s) + 3C(s) ↔ CaC2(s) + CO (g)

CaC2(s) + 2H2O(l) → C2H2(g) + Ca(OH)2(s)

Calcium Carbide, CaC2

CaSO4.2H2O : Gypsum

CaSO4.1/2H2O : Plaster of Paris

• Gypsum is a white substance and

used for fabrication into wallboard.

Calcium Sulfate, CaSO4

Uses

• Very light element

• To prepare some special alloys.

• 2% Be in Cu alloy in springs.

• Making glass for X-ray tubes.

• In the aerospace industry.

Beryllium

Uses

• Light metal

• Production of planes, missiles

• Some light household items.

• Flash in photography

Magnesium

• To increase the hardness, durability and

resistance to corrosion of alloys.

• Additive in rocket fuels and signal

rockets.

• Mg(OH)2 is used as a stomach antacid.

Magnesium

• Construction materials, bleaching agents.

• CaO in the production of some chemicals, steel, glass, paper

and sugar.

• CaC2 is used to produce acetylene gas

for welding.

• In fertilizers and

toothpaste

Calcium Compounds

• Ba is used as a gas absorbent in vacuum tubes.

• The alloys of Ba with Ni donate electrons so used in vacuum

tubes and in ignitors and spark plugs.

• Barium nitrate and barium chlorate are used to obtain green

light in fireworks.

Barium and Its Compounds

• BaSO4 is used to take the photos of stomach and intestines.

• Ba does not allow X-rays to pass like all elements with large

atomic number.

•The Ba+2 ion is toxic, but since the solubility of BaSO4 in

water is very low, its poisonous effect disappears.

Barium and Its Compounds

• The salts of strontium in signal rockets and fireworks to

produce red light.

• Nuclear batteries.

Strontium

• In self luminous paints and in radiotherapy.

• As a neutron source.

• On luminous watch dials.

Radium