An element has the electron configuration [Ar] 3d⁵ 4s¹. Which of the following statements about this element is correct?
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Correct answer
A. It is a transition metal located in Group 6 of the periodic table.
Principle or equation
The periodic table is organized by electron configurations. Elements with partially filled d orbitals are transition metals. The group number for transition metals often corresponds to the sum of the outermost s and d electrons.
Why this answer is correct
The configuration [Ar] 3d⁵ 4s¹ indicates that the d subshell is partially filled (5 electrons), making it a transition metal. The sum of 4s and 3d electrons is 6, placing it in Group 6. The element is chromium (Cr). Period is determined by the highest principal quantum number, which is 4, not 3.
Example
For [Ar] 3d⁷ 4s² (cobalt), the sum is 9, placing it in Group 9.
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