Group II - Alkaline Earth Metals

alkaline earth metals

Be, Mg, Ca, Sr, Ba, Ra

alkaline earth metal structures

form close packed lattices, harder metals with higher density than group I metals, make basic solutions

Natural forms of alkaline earth metals

Mineral Ores

Beryl

3BeO . Al2O3 . 6SiO2

Dolomite

CaCO3 . MgCO3

Calcite/argonite

CaCO3

extraction of pure group II metals

Mg is only one that can be extracted on industrial scale

electrolytic of chemical molten mineral halide 

Thermite Reaction

aluminum reacting with alkaline earth metal oxides to form the pure metal and aluminum oxide

Uses of Mg

high reactivity is helpful in photographic flashes, fireworks and flares; low density makes it valuable in alloys

Uses of alkaline earth metals

used in aircrafts and satellites, often used in Cu alloys, Be is used in the window of an X-ray apparatus

MgO

prepared by heating carbonate or hydroxide, very stable with mp= 2800 degrees, lattice energy high due to similar size of ions

Mg(OH)2

mild base, only partially soluble in water, prepared from magnesium and water or from precipitation of seas water with Ca(OH)2, used widely in anti-acid tablets

Coordination Compounds

Cyclic polyethers that can bind metals and “hide” a M+ cation inside the body; Mg forms important ones including chlorophyll in plants

Calcium

Important biologically, found in tooth enamel and bones; important geologically, contributes to acid rain

Beryllium

toxic by inhalation, forms beryllate with hydroxide ions, forms BeCl2 which acts like a lewis base, forms good hard conductors as an alloy with copper

Reaction of M with Hydrogen

Forms MH₂; does not work for Be or Mg

Reaction of M with O2

Forms MO

Ba forms BaO2

Reaction of M with N2

only works for magnesium

forms Mg3N2

Reaction of M with X2, a halogen

forms MX2 for all M

Reaction of M with water

forms M(OH)2; does not work for Be

anomalous properties of lithium

arise due to diagonal relationship with Mg

forms an Oxide

lattice energies are high when cation:anion radii are similar

small cation induces covalent character into bonding