1. Alkaline Earth Metals Beryllium Magnesium Strontium Radium Barium
Calcium

2. Alkaline Earth Metals
Why were these elements called “alkaline earth metals”?
What do you think about the uses of these elements commonly?

4. Properties
Beryllium
Magnesium
Calcium
Earth`s crust abundance
1.9x10 -4
2.9 5
Electron configuration
[He]2s2
[Ne]3s2
[Ar]4s2
Melting point (oC)
1287
650
842
Boiling point (oC)
2469
1090
1484
Density
1.85
1.74
1.55
Common oxidation num. +2
Physical State
solid
Color
grey
white
White

5. 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.

6. 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.

7. Characteristic Flame Colors of
Alkaline Earth Metals
Calcium
Strontium
Barium
Magnesium

8. All isotopes are radioactive
Minerals of Some Alkaline Earth Metals
Beryllium
Calcium
Barium
Beryl,
Be3Al2(SiO3)6
Limestone (marble),
CaCO3
Barytes,
BaSO4
Magnesium
Gypsum,
CaSO4.2H2O
Witherite,
BaCO3
Dolomite,
CaCO3. MgCO3
Fluorite,
CaF2
Radium
Carnallite,
KCI.MgCI2.6H2O
Strontium
All isotopes are radioactive
Epsom salt,
MgSO4.7H2O
Celestite,
SrSO4
Strontianite,
SrCO3

9. 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.

10. 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) → CaCl H2(g)
Be (s) + 2HCI(aq) → BeCI H2(g)
All oxides and hydroxides of alkaline earth metals show basic properties.
Oxides and its hydroxides of beryllium show amphoteric properties.

11. 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.

12. Calcium Oxide, CaO
Obtained by heating calcium carbonate (limestone) at 900°C.
CaCO3(s) → CaO(s) + CO2(g)
Calcium Carbonate, CaCO3
It forms by evolving CO2
gas from Ca(OH)2 solution.

13. Calcium Carbide, CaC2
Small gray solid pieces
Used widely in industry
Prepared by the reaction of calcium oxide (lime) and coke.
CaO(s) C(s) ↔ CaC2(s) + CO (g)
CaC2(s) H2O(l) → C2H2(g) + Ca(OH)2(s)

14. Calcium Sulfate, CaSO4
CaSO4.2H2O : Gypsum
CaSO4.1/2H2O : Plaster of Paris
Gypsum is a white substance and used for fabrication into wallboard.

15. Uses Beryllium 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.

16. Uses Magnesium Light metal Production of planes, missiles
Some light household items.
Flash in photography

17. 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.

18. Calcium Compounds
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

19. Barium and Its 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.

20. 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.

21. Strontium
The salts of strontium in signal rockets and fireworks to produce red light.
Nuclear batteries.

22. Radium
In self luminous paints and in radiotherapy.
As a neutron source.
On luminous watch dials.