Question

The shielding of electrons gives rise to an effective nuclear charge, Z_{\rm eff}, which explains why boron is larger than oxygen. Estimate the approximate Z_{\rm eff} felt by a valence electron of boron and oxygen, respectively?

A. +5 and +8
B. +3 and +6
C. +5 and +6
D. +3 and +8
E. +1 and +4

Answer 1

B. +3 and +6

Step-by-step explanation:

The values of the Z
`_(eff)` is estimated by subtracting the core electrons from the atomic number of the element.

Oxygen has an atomic number of 8, 6 valence electrons, and 2 core electrons. Therefore the value of Z
`_(eff)` = 8-2 = +6

Boron has an atomic number of 5, 3 valence electrons and 2 core electrons. Therefore, the value of Z
`_(eff)` = 5-2 = +3