To determine which of the given options has the maximum number of unpaired electrons, we will analyze the electronic configurations of each ion step by step.
### Step 1: Analyze Fe³⁺
- **Electronic Configuration**: Fe (Iron) has an atomic number of 26. Its ground state electronic configuration is:
\[
1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^6 \, 4s^2
\]
- When Fe loses 3 electrons to become Fe³⁺, it loses the 4s electrons first and then one 3d electron:
\[
\text{Fe}^{3+}: 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^5
\]
- **Unpaired Electrons**: In the 3d subshell (which can hold a maximum of 10 electrons), there are 5 electrons. According to Hund's rule, all 5 electrons will be unpaired.
- **Total Unpaired Electrons in Fe³⁺**: 5 unpaired electrons.
### Step 2: Analyze Fe²⁺
- **Electronic Configuration**: For Fe²⁺, we remove 2 electrons:
\[
\text{Fe}^{2+}: 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^6
\]
- **Unpaired Electrons**: In the 3d subshell, there are 6 electrons. The arrangement will be:
\[
\uparrow \, \uparrow \, \uparrow \, \uparrow \, \downarrow \, \downarrow
\]
- **Total Unpaired Electrons in Fe²⁺**: 4 unpaired electrons.
### Step 3: Analyze Co²⁺
- **Electronic Configuration**: For Co (Cobalt), which has an atomic number of 27:
\[
1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^7 \, 4s^2
\]
- For Co²⁺, we remove 2 electrons:
\[
\text{Co}^{2+}: 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^7
\]
- **Unpaired Electrons**: In the 3d subshell, there are 7 electrons. The arrangement will be:
\[
\uparrow \, \uparrow \, \uparrow \, \uparrow \, \downarrow \, \downarrow \, \downarrow
\]
- **Total Unpaired Electrons in Co²⁺**: 3 unpaired electrons.
### Step 4: Analyze Co³⁺
- **Electronic Configuration**: For Co³⁺, we remove another electron:
\[
\text{Co}^{3+}: 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^6
\]
- **Unpaired Electrons**: In the 3d subshell, there are 6 electrons. The arrangement will be:
\[
\uparrow \, \uparrow \, \uparrow \, \uparrow \, \downarrow \, \downarrow
\]
- **Total Unpaired Electrons in Co³⁺**: 4 unpaired electrons.
### Conclusion
Now we summarize the number of unpaired electrons for each ion:
- Fe³⁺: 5 unpaired electrons
- Fe²⁺: 4 unpaired electrons
- Co²⁺: 3 unpaired electrons
- Co³⁺: 4 unpaired electrons
**Final Answer**: The ion with the maximum number of unpaired electrons is **Fe³⁺** with **5 unpaired electrons**.
