Select the electron configurations for
(a) Co3+
[Ar]3d5
[Ar]3d6
[Ar]3d7
[Ar]4s13d5
[Ar]4s13d6
[Ar]4s13d7
[Ar]4s23d4
[Ar]4s23d5
[Ar]4s23d6
(b) Cu2+
[Ar]3d8
[Ar]3d9
[Ar]3d10
[Ar]4s13d8
[Ar]4s13d9
[Ar]4s13d10
[Ar]4s23d8
[Ar]4s23d9
[Ar]4s23d10
(c) Ag+
[Kr]4d8
[Kr]4d9
[Kr]4d10
[Kr]5s14d8
[Kr]5s14d9
[Kr]5s14d10
[Kr]5s24d8
[Kr]5s24d9
[Kr]5s24d10
The Correct Answer and Explanation is:
To determine the correct electron configurations for the ions Co³⁺, Cu²⁺, and Ag⁺, we need to consider their atomic configurations and how they change when the atoms lose electrons to form positive ions.
(a) Co³⁺ (Cobalt ion)
Cobalt (Co) has an atomic number of 27, so its ground state electron configuration is:
[
\text{Co: } [Ar] 4s^2 3d^7
]
When cobalt loses three electrons to form Co³⁺, the electrons are removed first from the 4s orbital before the 3d orbital due to the higher energy of the 4s level when filled. Thus, we first remove the two 4s electrons and one electron from the 3d orbital, resulting in the configuration:
[
\text{Co³⁺: } [Ar] 3d^6
]
Correct answer for Co³⁺:
[Ar] 3d⁶
(b) Cu²⁺ (Copper ion)
Copper (Cu) has an atomic number of 29, and its ground state electron configuration is:
[
\text{Cu: } [Ar] 4s^2 3d^{10}
]
When copper forms Cu²⁺, it loses two electrons. Similar to cobalt, the electrons are removed from the 4s orbital first, resulting in:
[
\text{Cu²⁺: } [Ar] 3d^9
]
Correct answer for Cu²⁺:
[Ar] 3d⁹
(c) Ag⁺ (Silver ion)
Silver (Ag) has an atomic number of 47, and its ground state electron configuration is:
[
\text{Ag: } [Kr] 5s^2 4d^{10}
]
For the formation of Ag⁺, silver also loses one electron, and it is again removed from the 5s orbital first. Thus, the electron configuration for Ag⁺ becomes:
[
\text{Ag⁺: } [Kr] 4d^{10}
]
Correct answer for Ag⁺:
[Kr] 4d¹⁰
Summary
The electron configurations for the ions are as follows:
- Co³⁺: [Ar] 3d⁶
- Cu²⁺: [Ar] 3d⁹
- Ag⁺: [Kr] 4d¹⁰
These configurations are significant because they help us understand the chemical properties and reactivity of these ions, particularly in transition metal complexes, where the number of d electrons plays a crucial role in bonding and magnetic properties. Understanding the electron configurations aids in predicting the behavior of these elements in various chemical reactions, including oxidation states, ligand interactions, and the formation of colored compounds.