## Chemistry: The Central Science (13th Edition)

The effective nuclear charge of Si is $+4$, while that of Cl is $+7$.
1) $Si$: The nuclear charge of Si is $Z=+14$. There are 10 core electrons and 4 valence electrons. Each core electron contributes 1.00 and each valence electron contributes 0.00 to the screening constant. Therefore, $S=10\times1.00+4\times0.00=10$ Therefore, the effective nuclear charge of Si is $$Z_{eff}=Z-S=+14-10=+4$$ 2) $Cl$: The nuclear charge of Cl is $Z=+17$. There are 10 core electrons and 7 valence electrons. Each core electron contributes 1.00 and each valence electron contributes 0.00 to the screening constant. Therefore, $S=10\times1.00+7\times0.00=10$ Therefore, the effective nuclear charge of Cl is $$Z_{eff}=Z-S=+17-10=+7$$