Question

question 2 of 10 which of the following notations is the correct noble gas configuration for co? a. ar4s²3d⁷ b. co4s²3d⁷ c. kr4s²4p⁶4d¹ d. ar4s²4p⁶3d¹

Explanation:

Cobalt (Co) has an atomic number of 27. The noble - gas core for Co is argon (Ar) which has 18 electrons. The remaining 9 electrons fill the 4s and 3d orbitals according to the Aufbau principle. The 4s orbital fills first with 2 electrons and then the 3d orbital fills with 7 electrons. So the noble - gas electron configuration for Co is [Ar]4s²3d⁷.

Answer:

A. [Ar]4s²3d⁷