How many electrons are in the outermost energy level of the Al3+ ion in its ground state? a) 2 b) 3 c) 6 d) 8
The Correct Answer and Explanation is:
The correct answer is a) 2.
Explanation:
To determine how many electrons are in the outermost energy level of the Al³⁺ ion, let’s break it down step by step.
- Determine the electron configuration of neutral aluminum (Al):
Aluminum (Al) has an atomic number of 13, which means it has 13 protons in the nucleus and, in its neutral state, 13 electrons. The electron configuration for a neutral Al atom is:
Al: 1s2 2s2 2p6 3s2 3p1\text{Al: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^1Al: 1s22s22p63s23p1
This means aluminum has 2 electrons in the first energy level (1s), 8 electrons in the second energy level (2s and 2p), and 3 electrons in the third energy level (3s and 3p). - Forming the Al³⁺ ion:
When aluminum forms an Al³⁺ ion, it loses 3 electrons. This happens because aluminum tends to lose electrons to achieve a stable electron configuration, similar to the nearest noble gas (in this case, neon).
The electron configuration of Al³⁺ is obtained by removing 3 electrons from the neutral aluminum atom:
Al³⁺: 1s2 2s2 2p6\text{Al³⁺: } 1s^2 \, 2s^2 \, 2p^6Al³⁺: 1s22s22p6
After the loss of 3 electrons, the electron configuration of the Al³⁺ ion is identical to that of neon (Ne), which has 10 electrons. - Identify the outermost energy level:
In the Al³⁺ ion, the outermost energy level is the second energy level (n=2), as the third energy level (n=3) is now empty after the loss of the 3 electrons.
The second energy level (n=2) contains 8 electrons in the 2s and 2p orbitals, but the outermost electrons are in the 2p subshell, which holds 2 electrons.
Therefore, the Al³⁺ ion has 2 electrons in its outermost energy level.
