Question

Which among the following is the sub shell electron configuration of chromium?

• A. [Ar] 3d 4s²
• B. [Ar] 3d 4s¹
• C. [Ar] 3d 4s²
• D. [Ar] 3d³ 4s²

Answer 1

Answer:

B. [Ar] 3d 4s¹

• Chromium is an exception to the expected electron configuration due to the extra stability provided by a half-filled d subshell. Instead of the expected [Ar] 3d⁴ 4s², one electron from the 4s orbital moves to the 3d orbital making it half-filled (3d⁵) and the 4s orbital has one electron (4s¹). This configuration is more stable energetically.