Question

q4 14. how many valence electrons are in copper (cu)? q5 ar 4s² 3d⁸ q6 ar 4s² 3d⁹ q7 ne 3s² 3p⁶ q8 kr 4s² 3d⁹ clear all

Explanation:

Step1: Recall copper's electron - configuration exception

Copper (Cu) has an atomic number of 29. Due to the stability of a full 3d - subshell, its electron - configuration is [Ar] 4s¹3d¹⁰ instead of the expected [Ar] 4s²3d⁹.

Step2: Identify valence electrons

Valence electrons are the electrons in the outermost shell. For copper, the outermost shell is the 4th shell, and it has 1 electron in the 4s orbital.

Answer:

1 (and the electron - configuration of copper is [Ar] 4s¹3d¹⁰)