Question

justify the position of carbon and lead in the periodic table on the basis of electronic configuration
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Answer 1

Hydrogen is the first element of the periodic table & often called protium. Its electronic configuration is [1s1]. Due to the presence of only one electron in its 1s shell, hydrogen exhibits a dual behaviour, i.e., it resembles both alkali metals and halogens. As a result it is placed at the top of the alkali metals in group 1 & also along the halogens in group 17 since just like halogens,it also requires any one electron to have the configuration of the nearest noble gas element..The dual nature of hydrogen can be justified by following points:

Resemblance with alkali metals:

1. Like alkali metals, hydrogen contains one valence electron in its valence shell.

H : 1s1

Li : 1s2 2s1

Na : 1s2 2s2 2p6 3s1

Hence, it can lose one electron to form a unipositive ion.