The physical and chemical properties of the elements are largely determined by their electronic structures:
- The Inert Gases (elements of ‘0’ group)
- The Representative Elements (‘s’ and ‘p’ block elements)
- The Transition Elements (‘d’ block elements)
- The Inner Transition Elements (‘f’ block elements)
1. The Inert Gases
(a) s2p6 arrangements in the outermost level,
(b) are very stable,
(c) He and Ne have complete energy level,
(d) very low reactivity,
(e) colourless gases.
**Why noble gases are chemically inactive?
Ans: Inactivity of the npble gases is due to- a) complete pairing of all electrons present, b) absence of any molecular orbital, c) stable energy state, d) very high ionization potential and e) negligible electron affinities.
2. The Representative Elements
(a) outermost energy level incomplete, just after s2 and s2p6 arrangements;
(b) chemical behaviour depends on valence electron,
(c) alkali metals, alkaline earth metals have valence electron in the ‘s’ orbital.
(d) group IIIA (under boron) has single electron in ‘p’ orbital,
(e) group IIIA-VIIA vertically occupy ‘p’ orbital,
(f) generally form colourless compounds.
3. The Transition Elements
(a) heavy metals of sub-group B, high melting and electropositive,
(b) contain two incomplete energy levels (‘s’ & ‘d’ orbitals),
(c) chemical properties depends upon the electron of the two outermost levels (‘s’ & ‘d’ orbitals),
(d) have almost the same atomic and ionic sizes,
(e) are effective catalytic agents,
(f) form quite a large number of complex compounds,
(g) show positive oxidation states of +2 and +3 generally and form mostly ionic compounds,
(h) generally form coloured compounds.
4. The Inner Transition Elements
(a) these elements have three incomplete outer levels (‘s’, ‘d’ & ‘f’ orbitals)
(b) ‘f’ orbitals are being completed,
(c) lanthanides (rare earths) and actinides (trans-uranium)
(d) the properties are similar to as in the case of transition elements.