Question

In one area of Australia, the cattle did not thrive despite the presence of suitable forage. An investigation showed the cause to be the absence of sufficient cobalt in the soil. Cobalt forms cations in two oxidation states, Co²⁺ and Co³⁺. Write the electron structure of the two cations.

a) Co²⁺: 1s²2s²2p⁶3s²3p⁶3d⁷
b) Co³⁺: 1s²2s²2p⁶3s²3p⁶3d⁶
c) Co²⁺: 1s²2s²2p⁶3s²3p⁶3d⁸
d) Co³⁺: 1s²2s²2p⁶3s²3p⁶3d⁵

Answer 1

Answer: A) and B)

Explanation: C) and D) do not make sense as the electron structure of regular cobalt is as follows.

1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^7

C) supports taking away two electrons from orbital 4s and adding an electron to orbital 3d which does not make sense. D) proposes taking away four electrons, two from 4s and two from 3d, which does not follow the charges to the cations that you are trying to make. Therefore, A) is correct as it takes away two electrons from 4s and follows the cation trying to be formed, and B) is correct as it takes away three electrons, two from 4s and one from 3d, which follows the cation trying to be formed.

Answer 2

The electron structure of Co²⁺ is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁷, while the electron structure of Co³⁺ is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵.

Step-by-step explanation:

The electron structure of Co²⁺ is: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁷

The electron structure of Co³⁺ is: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵

When cobalt forms cations, it can either lose two electrons and become Co²⁺ or lose three electrons and become Co³⁺. To determine the electron structure of the cations, we need to remove the appropriate number of electrons from the neutral cobalt atom. In the case of Co²⁺, we remove two electrons from the outermost shell, which is the 4th shell (3d and 4s subshells), resulting in the electron structure of 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁷. For Co³⁺, we remove three electrons from the 4th shell, resulting in the electron structure of 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵.