1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵
Here's a breakdown:
* 1s²: The first energy level (n=1) has 2 electrons in the s orbital.
* 2s² 2p⁶: The second energy level (n=2) has 2 electrons in the s orbital and 6 electrons in the p orbital.
* 3s² 3p⁶: The third energy level (n=3) has 2 electrons in the s orbital and 6 electrons in the p orbital.
* 4s² 3d⁵: The fourth energy level (n=4) has 2 electrons in the s orbital, and the 3d orbital has 5 electrons.
Important Note: You might see the electron configuration written as [Ar] 4s² 3d⁵ as well. This is a shorthand notation using the noble gas Argon ([Ar]) to represent the filled shells up to the 3p orbital.
