Question

why is hydrogen kept in 1st group although it acts act halogen and has valency -1

Answer 1

i think the hydrogen kept in 1 st group to satisfied the modern periodic law.
according to modern periodic table, if we arranged elements according to increasing atomic no. order, then the elements with same valence electron occur at regular interval.

so in 1st group every elements have 1 valence electron as like hydrogen .
so hydrogen is put in 1st group

Answer 2

i think the hydrogen kept in 1 st group to satisfied the modern periodic law.
according to modern periodic table, if we arranged elements according to increasing atomic no. order, then the elements with same valence electron occur at regular interval.

so in 1st group every elements have 1 valence electron as like hydrogen .
so hydrogen is put in 1st group

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