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

$Mg$: There are $2$ valence electrons in $Mg$ atom. Hence,the Lewis dot symbol is: $\cdot \dot{Mg} \cdot$ (or $\ddot{Mg}$)
$Na$: There is $1$ valence electron in $Na$ atom. Hence,the Lewis dot symbol is: $\dot{Na}$
$B$: There are $3$ valence electrons in $B$ atom. Hence,the Lewis dot symbol is: $\cdot \dot{B} \cdot$
$O$: There are $6$ valence electrons in $O$ atom. Hence,the Lewis dot symbol is: $:\ddot{O}:$
$N$: There are $5$ valence electrons in $N$ atom. Hence,the Lewis dot symbol is: $:\ddot{N}\cdot$
$Br$: There are $7$ valence electrons in $Br$ atom. Hence,the Lewis dot symbol is: $:\ddot{\underset{..}{Br}}:$