The atom having the valence-shell configuration $4s^2 4p^5$ would be in what group and period?

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Answer 1 · 2017-01-04T20:36:19

The atom would be in Period 4 and Group 17.

The valence shell configuration is $"4s"^2 "4p"^5$ .

The principal quantum number (4) gives you the Period number.

Start with H in Period 1 and count down to the fourth row (Period 4).

That brings you to $"K"$ .

Location
(Adapted from Chemistry - About.com)

Now, start counting to the right through the $"s"$ -block to $"Ca"$ ( $"4s"^2$ ) and the $"d"$ -block to $"Zn"$ .

Now that you have come to the $"p"$ -block, count five more atoms, for a $"4p"^5$ configuration.

This brings you to the desired atom, $"Br"$ .

You have counted horizontally through 17 atoms, so $"Br"$ is in Group 17.

The atom having the valence-shell configuration 4s^2 4p^54s^2 4p^5 would be in what group and period?