Question

How many valence electrons are there in the Al3+ ion? Briefly justify your answer.

Answer 1

First, let's write the electron configuration for Al (Atomic number 13):

[Al] = 1s² 2s² 2p⁶ 3s² 3p¹

In this, Al has 3 valence electrons, cause it last energy level, it's the 3, and in this it has 3 electrons.

Now,for Al³⁺

[Al³⁺] = 1s² 2s² 2p⁶

It acquires the electron configuration of Neon. Neon has 8 valence electrons, so, in theory, it has 8 valence electrons, but the 3+ charge means that it's missing 3 electrons, so it does not have valence electrons perse, just the corresponding to the second level of energy (configuration of Ne)

Hope this helps