The ground state electron configuration for the lithium ion is: 1s² 2s¹
The Correct Answer and Explanation is:
The correct ground state electron configuration for the lithium ion (Li⁺) is:
1s²
Explanation:
Lithium (Li) has an atomic number of 3, meaning it has 3 protons and, in its neutral state, 3 electrons. The ground state electron configuration of neutral lithium (Li) is:
1s² 2s¹
This means that:
- The first two electrons fill the 1s orbital
- The third electron goes into the 2s orbital
However, when lithium loses one electron to become a lithium ion (Li⁺), it loses that outermost electron from the 2s orbital. The electron is lost because Li⁺ is a cation, and cations are formed when atoms lose electrons.
Therefore, the electron configuration of Li⁺ becomes:
1s²
This reflects only the core electrons that remain after the loss of the 2s¹ electron.
Important Notes:
- Electron loss always occurs from the highest energy level first, which in this case is the 2s orbital.
- The 1s electrons are more tightly held by the nucleus and are not typically involved in ion formation for light elements like lithium.
- This electron configuration (1s²) matches that of helium, which is a noble gas. That means Li⁺ achieves a stable noble gas configuration when it loses one electron.
In summary, while neutral lithium is written as 1s² 2s¹, the lithium ion (Li⁺) has an electron configuration of 1s², since it has lost the single 2s electron during ionization.
