Question

How to find group number and period number

Answer 1

Explanation:

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Answer 2

The number of valence electrons in the atom determines the group number of that atom i.e. if an element has 4 valence electrons then it must belong to group IV A. Since sodium has 3 shells, it belongs to period 3. Also, we notice that this element has 1 electron in its outermost orbit therefore it belongs to group I A.

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