A lithium atom has three electrons, two in the 1s sublevel and one in the 2p sublevel.
The correct answer and explanation is:
The statement about the electron configuration of a lithium atom is incorrect. The correct electron configuration for a lithium (Li) atom, which has three electrons, is:
1s² 2s¹
Explanation:
Lithium has an atomic number of 3, meaning it has three electrons in its neutral state. The arrangement of these electrons follows the principle of filling lower energy orbitals first.
- First shell (n=1): The first energy level can hold a maximum of two electrons, and these electrons will fill the 1s orbital. Therefore, the two electrons of lithium occupy the 1s orbital, represented as 1s².
- Second shell (n=2): The second energy level begins to fill after the first shell is filled. The next available orbital is the 2s orbital, and since there is only one electron left to place in lithium, this electron occupies the 2s orbital, represented as 2s¹.
Thus, the correct electron configuration for lithium is 1s² 2s¹, meaning there are two electrons in the 1s sublevel and one electron in the 2s sublevel, not in the 2p sublevel. The 2p sublevel starts filling after the 2s sublevel, and in the case of lithium, the 2p sublevel remains unoccupied.
This configuration follows the Aufbau principle, which states that electrons fill orbitals starting from the lowest energy level and moving to higher ones. It also follows Hund’s rule and the Pauli exclusion principle, which govern the filling of orbitals and electron pairing.
Therefore, the correct configuration is 1s² 2s¹, not 1s² 2p¹.