Identify the correct abbreviated electron configuration for the zinc ion: Group of answer choices a. [Ar]4s23d8 b. [Ar]3d10 c. [Ar]4s23d10 d. [Ar]3d104s2
The Correct Answer and Explanation is:
Correct Answer:
b. [Ar]3d¹⁰
Explanation:
Zinc (Zn) has an atomic number of 30, which means a neutral zinc atom has 30 electrons. The electron configuration of a neutral Zn atom is:
Zn: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰
In abbreviated form, this is written as:
[Ar] 4s² 3d¹⁰
When zinc becomes a Zn²⁺ ion, it loses two electrons. Electrons are always lost from the outermost energy level first, which is the 4s orbital in this case—not the 3d orbital, even though the 3d sublevel is written after 4s. So we remove both electrons from the 4s orbital:
Zn²⁺: [Ar] 3d¹⁰
This gives us a full 3d subshell and no 4s electrons. The 3d orbitals are now completely filled, giving zinc ion a stable and symmetrical electron configuration.
Now let’s examine the answer choices:
- a. [Ar]4s²3d⁸ – Incorrect; this has two 4s electrons and only 8 in the 3d subshell, which does not match the Zn²⁺ configuration.
- b. [Ar]3d¹⁰ – Correct; this matches the expected configuration of Zn²⁺ after losing two 4s electrons.
- c. [Ar]4s²3d¹⁰ – Incorrect; this is the configuration of neutral Zn, not Zn²⁺.
- d. [Ar]3d¹⁰4s² – Incorrect; same as (c), just with a reversed order that still represents neutral Zn.
Therefore, the correct abbreviated electron configuration for the zinc ion Zn²⁺ is [Ar]3d¹⁰
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