Explain the crystalline structure by writing the electronic configuration of elementary semiconductors.

(N/A) Elementary semiconductors are $Si$ and $Ge$.
The atomic number of $Si$ is $Z=14$. Its electronic configuration is $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{2}$. The $K$ and $L$ shells are filled completely,and the $M$ shell $(n=3)$ is incomplete,containing four valence electrons $(3s^{2} 3p^{2})$.
The atomic number of $Ge$ is $Z=32$. Its electronic configuration is $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{10} 4s^{2} 4p^{2}$. The $K, L,$ and $M$ shells are filled completely,but the $N$ shell $(n=4)$ is incomplete,containing four valence electrons $(4s^{2} 4p^{2})$.
Thus,$Si$ and $Ge$ are tetravalent elements.
In their crystalline structure,every $Si$ or $Ge$ atom tends to share one of its four valence electrons with each of its four nearest neighbor atoms and also takes a share of one electron from each such neighbor.
These shared electron pairs form covalent bonds. Each bond contains two electrons.
The figure depicts one atom of $Ge$ or $Si$ covalently bonded with four neighboring atoms. The solid dots represent valence electrons. The figure is a two-dimensional representation,and the $+4$ symbol indicates the inner core of the $Si$ or $Ge$ atom.
Each of the bonded electrons is tightly bound to the atoms it connects.