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The S-Block Elements

Question
CBSEENCH11007067

Name the elements of group 1. Write their electronic configurations.

Solution

The metallic elements lithium (Li), sodium (Na), potassium(K), rubidium (Rb), caesium (Cs) and francium (Fr) constitute group 1 of the periodic table. Francium is a radioactive element. They are known as alkali metals because their hydroxides are strong alkalies or bases.
Electronic configuration: The atoms of alkali metals have one electron in s-orbital outside a noble gas core. Therefore, their general electronic configuration is:
[Noble gas]ns1 where n = 2 to 7
The electronic configurations of alkali metals are given below:

Element At No Electronic configuration
Lithium (Li) 3 [He]2s1
Sodium (Na) 11 [Ne] 3s1
Potassium (K) 19 [Ar] 4s1
Rubidium (Rb) 37 [Kr] 5s1
Caesium (Cs) 55 [Xe] 6s1
Francium (Fr) 87

[Rb] 7s1