Write Lewis dot symbols for atoms of the following elements: $Mg, Na, B, O, N, Br$.

(N/A) Lewis dot symbols represent the valence electrons of an atom as dots around the chemical symbol.
$Mg$ (Group $2$): $2$ valence electrons $\rightarrow \cdot Mg \cdot$
$Na$ (Group $1$): $1$ valence electron $\rightarrow Na \cdot$
$B$ (Group $13$): $3$ valence electrons $\rightarrow \cdot \dot{B} \cdot$
$O$ (Group $16$): $6$ valence electrons $\rightarrow \cdot \ddot{O} \cdot \cdot$
$N$ (Group $15$): $5$ valence electrons $\rightarrow \cdot \ddot{N} \cdot \cdot$
$Br$ (Group $17$): $7$ valence electrons $\rightarrow \cdot \ddot{Br} \cdot \cdot \cdot$