Classification of Elements and Periodicity in Properties
Valency, Oxidation states and Chemical reactivity
Oxidation State / Oxidation Number :
The amount of charge appears to be gained by an atom in a molecule is called oxidation state.
ex : O-2, F-, N-3, S-2 -----
Inert pair effect :
s- orbitals behave like inert gas because it is strongly attracted by nucleus cause poor shielding
→ Thallium = 6s2 6p1
Tl+ = stable
Down the group, oxidation state decreases so more stable.
Pb+2 > Pb+4 (stability)
Diagonal relationship :
element of a group in 2nd period resembles in its properties.
Reasons for diagonal relationship :
→ Nearly same atomic and ionic size
→ Nearly same electronegativity
→ Nearly same polarising power.
\tt Polarising \ power = \frac{Ionic \ character}{(Ionic \ radius)^{2}}
Be and Al are amphoteric.
Part1: View the Topic in this Video from 0:11 to 11:03
Part2: View the Topic in this Video from 0:12 to 11:52
Part3: View the Topic in this Video from 0:16 to 6:37
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