(1) Physical state : Oxygen is gas while all other are solids.
(2) Atomic radii : Down the group atomic radii increases because the increases in the number of inner shells overweighs the increase in nuclear charge.
(3) Ionization energy : Down the group the ionization energy decrease due to increase in their atomic radii and shielding effect.
(4) Electronegativity : Down the group electronegativity decreases due to increase in atomic size.
(5) Electron affinity : Element of this group have high electron affinity, electron affinity decreases down the group.
(6) Non – metallic and metallic character : These have very little metallic character because of their higher ionisation energies.
(7) Nature of bonding : Compounds of oxygen with non metals are predominantly covalent. S, Se, and Te because of low electronegativities show more covalent character.
(8) Melting and boiling points : The melting point and boiling points increases on moving down the group.
(9) Catenation : Oxygen has some but sulfur has greater tendency for catenation.
H - O - O - H, H - S - S - H,
( H2O2 ) ( H2S2 )
H - S - S - S - H, H - S - S - S - S - H
(H2S3) (H2S4)
(10) Allotropy
Oxygen – |
O2 and O3
|
Sulphur – |
Rhombic , monoclinic, plastic sulphur |
Selenium – |
Red (non-metallic) grey (metallic) |
Tellurium – |
Non-metallic and metallic (more stable) |
Polonium – |
α and ß (both metallic) |
|
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