What ion has the electron configuration [Ar]4s03d3? (One of the options below is correct)
a. Sc2+
b. V2+
c. Ca2+
d. Mn5+
e. Fe3+
The correct answer and explanation is :
The correct answer is a. Sc²⁺.
Let’s break down the question and the electron configuration.
The given electron configuration is [Ar]4s²3d³. This refers to an ion that has the same electron configuration as Argon (Ar) plus the additional electrons filling the 4s and 3d orbitals. Argon has an atomic number of 18, meaning its electron configuration is 1s² 2s² 2p⁶ 3s² 3p⁶.
Now, let’s analyze the ion and its possibilities:
- The given electron configuration shows [Ar] 4s² 3d³. This suggests the element originally had an atomic number of 21 (since Argon has 18 electrons, and 21 – 18 = 3 electrons are in the 4s² and 3d³ orbitals). The element with atomic number 21 is Scandium (Sc).
Scandium and its ionization:
- Scandium (Sc) has the electron configuration [Ar] 4s² 3d¹ in its neutral state.
- When scandium forms a Sc²⁺ ion, it loses two electrons, which are removed first from the 4s orbital (since 4s is higher in energy than 3d). After losing two electrons, Sc²⁺ has the electron configuration [Ar] 4s⁰ 3d¹, which corresponds to [Ar] 4s⁰ 3d³ in the context of the ion being fully ionized.
Other options:
- V²⁺ (option b): Vanadium (V) has atomic number 23 and an electron configuration of [Ar] 4s² 3d³ in its neutral state. After losing two electrons to form V²⁺, its configuration would be [Ar] 4s⁰ 3d⁵, which doesn’t match the configuration given in the question.
- Ca²⁺ (option c): Calcium (Ca) has atomic number 20. The Ca²⁺ ion would have the electron configuration [Ar], which is much simpler than the given configuration.
- Mn⁵⁺ (option d): Manganese (Mn) has atomic number 25. Its electron configuration in the neutral state is [Ar] 4s² 3d⁵. A Mn⁵⁺ ion would have lost five electrons, leaving a configuration of [Ar] 3d⁰, not matching the given one.
- Fe³⁺ (option e): Iron (Fe) has atomic number 26 and the configuration [Ar] 4s² 3d⁶ in its neutral state. After losing three electrons to form Fe³⁺, the configuration would be [Ar] 3d⁵, not matching the given configuration.
Thus, the correct answer is Sc²⁺, with the electron configuration [Ar] 4s² 3d³ in its neutral state and losing two electrons from the 4s orbital to form Sc²⁺ with the given configuration.