How can we know group and period of an element by knowing its atomic n

1.	How can we know group and period of an element by knowing its atomic number
Answer» Thankyou No. of shells represent periods and no. of valence electron represent group.(if the valence electron is 3 or more than three add 10 to it,e.g. Valence electron =3 then group=13) The number of shell will give us the period number and it\'s valence electron will give us the group number

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