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.