Multiple Choice
Why do chemists use the electron cloud or charge density model to describe electrons in atoms?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following is the correct electron configuration for the Mn^{2+} cation?
A
[Ar] 3d^3 4s^2
B
[Ar] 3d^4 4s^1
C
[Ar] 3d^5
D
[Ar] 3d^6
Verified step by step guidance1
Step 1: Identify the atomic number of manganese (Mn), which is 25. This means a neutral Mn atom has 25 electrons.
Step 2: Write the electron configuration for the neutral Mn atom. The full configuration is $[Ar] 3d^5 4s^2$, where $[Ar]$ represents the argon core with 18 electrons.
Step 3: Understand that the Mn$^{2+}$ cation has lost 2 electrons compared to the neutral atom, so it has 23 electrons.
Step 4: Remove electrons first from the outermost shell, which is the 4s orbital, before removing from the 3d orbitals. So, remove 2 electrons from the $4s^2$ electrons.
Step 5: After removing the 2 electrons from the 4s orbital, the electron configuration for Mn$^{2+}$ becomes $[Ar] 3d^5$.
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