For carbon: What is the effective nuclear charge? In which orbitals do the valence electrons reside? For silicon: What is the effective nuclear charge? In which orbitals do the valence electrons reside?

For carbon, the effective nuclear charge is 3.25 and the valence electrons will reside in the orbitals 2s^2 and 2p^2

For silicon, the effective nuclear charge is 4.15 and its valance electrons will reside in the orbitals 3s^2 and 3p^2

Explanation:

Carbon

The effective nuclear charge of carbon is 3.25

To get the orbitals in which it’s valence electron reside, let’s write the electronic configuration

The atomic number of carbon is 6

So the configuration will be;

1s^2 2s^2 2p^2

So the valence electrons will reside in the orbitals 2s^2 and 2p^2

For silicon;

It’s effective nuclear charge is +4.15

The electronic configuration of silicon with atomic number 14 is;

1s^2 2s^2 2p^6 3s^2 3p^2

So the valence electrons will reside in the orbitals 3s^2 and 3p^2