Which electron configurations represent the first two elements in Group 17 (7A) of the Periodic Table?
A
1s22s1 and 1s22s2

B
1s22s22p6 and [Ne]3s23p5

C
1s22s22p5 and [Ne]3s23p5

D
1s22s2 and 1s22s22p1

Option C is correct

1s22s22p5 and [Ne]3s23p5

Explanation:

Step 1: Data given

Group 17 = the halogens

Halogens have 7 valence electrons

The first element of group 17 = Fluorine (F)

Fluorine has 9 electrons

The electron configuration is

1s2 2s2 2p5

The second element of group 17 = Chlorine (Cl)

Chlorine has 17 electrons

The electron configuration is

1s2 2s2 2p6 3s2 3p5

Option C is correct

1s22s22p5 and [Ne]3s23p5

c, liquids evaporate, creating a gas