An atom of an element has the electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵. Which of the following statements about this element is correct?
Show the answer and explanation
Correct answer
A. It is a transition metal located in period 4 and group 7.
Principle or equation
The periodic table position is determined by the highest occupied principal energy level (period) and the number of electrons in the outermost s and d orbitals (group for transition metals).
Why this answer is correct
The configuration ends with 4s² 3d⁵. The highest principal quantum number is 4, so the element is in period 4. For transition metals, the group number is the sum of the 4s and 3d electrons: 2 + 5 = 7, so it is in group 7. It is a transition metal (d-block).
Example
For [Ar] 3d⁶ 4s², period 4, group 8 (iron).
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