Answer:
The valency of an element refers to the number of electrons an atom can gain, lose or share to attain a stable configuration.
Aluminum (Al) is a metal with an atomic number of 13, which means it has 13 electrons in its neutral state. In its outermost shell, aluminum has three valence electrons.
To attain a stable electronic configuration, aluminum can lose these three valence electrons to become a cation with a 3+ charge (Al3+). By losing these electrons, the outermost shell of the aluminum atom becomes completely filled with eight electrons, which is a stable configuration.
Therefore, the valency of aluminum is 3 because it can lose three electrons to form a stable cation with a 3+ charge.
Step-by-step explanation: