aluminiums electron configuration is (1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}). …

$aluminiums electron configuration is (1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}). …$

aluminiums electron configuration is (1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}). aluminium has ____ valence electron(s).

Valence shell is the outermost shell. Here, it's $3s$ and $3p$ (third shell).

In $3s^{2}$, there are $2$ electrons. In $3p^{1}$, there is $1$ electron. Total valence electrons $=2 + 1$.

$3$