Group 2 physical properties part 1

Group 2 (alkaline earth metals) physical properties (Chapter 11-Part 2):
The reason behind naming group 2 alkaline earth metals is that they form alkaline solution when dissolve in water.
Metallic radius is half the distance between the nuclei in a giant metallic lattice.
Metallic radius increases down group 2 because the atomic number increases and extra level is added down the group
Group 2 have high electric conductivity and the thermal conductivity.
Group 2 melting point trend:
Melting points decrease down the group although some irregularities are seen.
The reason behind the low melting point of magnesium comparing to calcium is the arrangement of metallic lattice for both elements.
• Be 1544, 1560, 1018, hcp (face centered cubic) at RT
• Mg 922, 755, 705, hcp (hexagonal close packed) at RT
• Ca 940, 1114, 1063, fcc at RT
• Sr 900, 1050, 1030, fcc at RT
• Ba 635, 1000, 709, bcc (body center cubic) at RT
Calcium has fcc arrangement where magnesium has hcp crystal packing, the high ductility makes melting point of calcium higher than magnesium.
Density trend for group 2 elements:
Density increases down group 2 as atomic number increases.
Again, some irregularities in density are also seen, calcium has lower density than magnesium. Crystal lattice of calcium has 14 atoms where magnesium has 19 atoms in its lattice which makes density of calcium lower than magnisium.
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