Consider these elements: n, mg, o, f, al. a. write the electron configuration for each element. b. arrange the elements in order of decreasing atomic radius. c. . d. use the electron configurations in part a to explain the dif- ferences between your answers to parts b and c.

N- 1s2 2s2 2p3

Mg- 1s2 2s2 2p6 3s2

O- 1s2 2s2 2p4

F- 1s2 2s2 2p5

Al-1s2 2s2 2p6 3s2 3p1

Explanation:

Order of decreasing atomic radius

Mg,Al, N,O,F

Order of increasing ionization energy

Mg,Al, N,O,F

Reason:

Atomic radius decreases with increase in nonmetallic character. Looking at the electronic configurations, as effective nuclear charge increases, the atom becomes smaller and the attractive force between the nucleus and the outermost electrons increases. Hence, the radius of the atom decreases and ionization energy increases. Note that the addition of more orbital electrons implies addition of more nuclear charge since the both must exactly balance for the atom to remain electrically neutral. The more the electrons in the outermost shell, the higher the first ionization energy.