Which is the electron configuration for lithium?
A. 1s2
B. 2s3
C. 1s22s1
D. 1s12s2
The Correct Answer and Explanation is :
The correct answer for the electron configuration of lithium is C. 1s²2s¹.
Explanation:
Understanding Electron Configuration:
Electron configuration describes the distribution of electrons in an atom’s atomic orbitals. For lithium, which has an atomic number of 3, this means it has three electrons.
Filling the Orbitals:
- First Shell (n=1): The first shell can hold up to 2 electrons in the 1s orbital. According to the Aufbau principle, electrons fill the lowest energy orbitals first. Therefore, the first two electrons of lithium occupy the 1s orbital:
- 1s²: This notation indicates that there are 2 electrons in the 1s orbital.
- Second Shell (n=2): The next electron will occupy the 2s orbital. Since lithium has a total of three electrons, the third electron will fill the 2s orbital:
- 2s¹: This notation indicates that there is 1 electron in the 2s orbital.
Combining the Configurations:
When combining these, the complete electron configuration for lithium is written as:
- 1s²2s¹
Why the Other Options Are Incorrect:
- A. 1s²: This only accounts for 2 electrons and does not include the third electron.
- B. 2s³: This suggests that there are 3 electrons in the 2s orbital, which is incorrect, as the 2s orbital can hold a maximum of 2 electrons.
- D. 1s¹2s²: This suggests that there is only 1 electron in the 1s orbital and 2 in the 2s orbital, which misrepresents the distribution of electrons.
In summary, lithium’s electron configuration correctly represents its three electrons as 1s²2s¹, with 2 electrons filling the 1s orbital and 1 electron in the 2s orbital, following the principles of electron filling and the maximum capacities of the orbitals.