My book says the number of outermost electrons in silicon is $4$. Yes, right. But then it says those are $\ce{2s}$ and $\ce{2p}$ electrons. The electronic configuration of silicon is $\ce{1s^2 2s^2 2p^6 3s^2 3p^2}$. How are the outermost electrons $\ce{2s}$ and $\ce{2p}$ electrons. Those belong to third shell. Then it says the maximum number of electrons in the outermost shell is $8$. Correct. But then it says those are $\ce{2s + 6p}$ electrons. How?