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Question
Write down the electronic configuration of the following elements from the given atomic numbers. Answer the following question with explanation.
3Li, 14Si, 2He, 11Na, 15P Which of these elements belong to be period 3?
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Solution
3Li, 14Si, 2He, 11Na, 15P
Electronic configuration of the following elements is:
3Li = 2,1
14Si = 2,8,4
2He = 2
11Na = 2,8,1
15P = 2,8,5
14Si, 11Na, 15P belong to the third period because according to their electronic configuration, each element contains three shells i.e. K,L,M.
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