What is the electron configuration for Al? Al+3? What noble gas is Al 3+ isoelectronic with?
The correct answer and explanation is:
Correct Answer:
- Electron configuration for Al (Aluminum): 1s² 2s² 2p⁶ 3s² 3p¹
- Electron configuration for Al³⁺ (Aluminum ion): 1s² 2s² 2p⁶
- Al³⁺ is isoelectronic with the noble gas Neon (Ne)
Explanation (300 words):
Aluminum (Al) is a metallic element with an atomic number of 13. This means it has 13 protons in its nucleus and, in its neutral state, also 13 electrons surrounding the nucleus. The electrons in an atom are arranged in energy levels or shells following the Aufbau principle, which states that electrons fill lower energy orbitals first before moving to higher ones.
The electron configuration for a neutral aluminum atom is written as 1s² 2s² 2p⁶ 3s² 3p¹. This configuration shows that aluminum has two electrons in the first energy level (1s²), eight electrons in the second energy level (2s² 2p⁶), and three electrons in the third energy level (3s² 3p¹).
When aluminum forms a +3 ion (Al³⁺), it loses three electrons. These electrons are removed starting from the outermost shell, which in this case is the third energy level. The first electron removed comes from the 3p orbital, and the next two from the 3s orbital. After removing all three, the configuration becomes 1s² 2s² 2p⁶, which contains only the first and second energy levels.
This electron configuration (1s² 2s² 2p⁶) is identical to that of neon (Ne), a noble gas with an atomic number of 10. Since Al³⁺ and Ne have the same number of electrons and the same configuration, they are isoelectronic. Isoelectronic species are atoms or ions that have the same number of electrons and the same electronic structure, although they differ in the number of protons and identity.
Understanding these configurations is essential for predicting chemical reactivity, bonding behavior, and stability of atoms and ions. Al³⁺, having a noble gas configuration, is relatively stable due to its full outer shell.