Page 1 - Microsoft Word - Module-1

SUBJECT – CHEMISTRY

S-BLOCK ELEMENTS

SUB TOPIC: GROUP - 1 ELEMENTS (ALKALI METALS), TRENDS
IN ATOMIC PROPERTIES, PHYSICAL PROPERTIES, CHEMICAL

PROPERTIES, USES OF ALKALI METALS.

KEY NOTES:

TRENDS IN ATOMIC PROPERTIES:

 Group - 1 elements are Li, Na, K, Rb, Cs, Fr

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 General electronic configuration is ns .
 Down the group atomic and ionic radii increases.

 Ionization enthalpies of alkali metals are low and

decreases down the group.

 Hydration enthalpies of alkali metal ions decreases

with increase in ionic size.

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+
Li > Na > K > Rb > Cs
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+
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TRENDS IN PHYSICAL PROPERTIES:

 Alkali metals are silvery white, soft and light metals.

 Down the group density decreases.

 They have low melting point and boiling point due to

weak metallic bonding.

 Impart characteristic colour to flame.