10.
$NH_4^+$: $7+1.4-1=10e$
$NO_3^-$: $7+8.3+1=32$
$CO_3^{2-}$: $6+8.3+2=32e$
$PO_4^{3-}$: $15+8.4+3=50e$
$Br^-$: $35+1=36e$
$K^+$: $19-1=18e$
$Ca^{2+}$: $20-2=18e$
$S^{2-}$: $16+2=18e$
7.
a,
$Na+$: $1s^2$ $2s^2$ $2p^6$
$Al^{3+}$: $1s^2$ $2s^2$ $2p^6$
$K^+$: $1s^2$ $2s^2$ $2p^6$ $3s^2$ $3p^6$
$Ca^{2+}$: $1s^2$ $2s^2$ $2p^6$ $3s^2$ $3p^6$
b,
$Cl^-$: $1s^2$ $2s^2$ $2p^6$ $3s^2$ $3p^6$
$S^{2-}$: $1s^2$ $2s^2$ $2p^6$ $3s^2$ $3p^6$
$N^{3-}$: $1s^2$ $2s^2$ $2p^6$
8.
+ $Mg^{2+}$:
$n=24-12=12$
$p=12$
$e=12-2=10$
+ $O^{2-}$:
$n=16-8=8$
$p=8$
$e=8+2=10$
+ $F^-$:
$n=19-9=10$
$p=9$
$e=9+1=10$
