Estimate the approximate zeff felt by a valence electron of carbon and oxygen. Assume that the shielding of electrons within the same shell is negligible.

Oxygen : 6.3

Carbon : 4.3

Explanation:

The steps to calculate the Zeff is:

1) Write the electronic configuration.

Carbon: 1s2 2s2 2p2

Oxygen: 1s2 2s2 2p4

2) there are two core electrons in each atom and four in carbon and six in oxygen.

(1s) (2s2p)

3) as mentioned the shielding of electrons within the same shell is negligible.

4) for electron of s or p orbital the shielding contribution by the electrons having a principal quantum number less by one would be 0.85 each. And all electrons further left would contribute an amount of 1.0 each.

5) For oxygen:

Zeff = Z - S

S = 2X0.85 = 1.7

Zeff = 8 - 1.7 = 6.3

For carbon

Zeff = Z - S

S = 2X0.85 = 1.7

Zeff = 6 - 1.7 = 4.3