To determine which of the following ions is not isoelectronic with the other three, we need to calculate the total number of electrons in each ion. Isoelectronic species are those that have the same number of electrons.
Let's analyze each ion step by step:
1. **CO3^2- (Carbonate Ion)**:
- Carbon (C) has 6 electrons.
- Each Oxygen (O) has 8 electrons, and there are 3 Oxygen atoms.
- Therefore, the total number of electrons from Oxygen is: 8 * 3 = 24.
- The ion has a -2 charge, which means there are 2 extra electrons.
- Total electrons = 6 (C) + 24 (O) + 2 (extra) = 32 electrons.
2. **NO3^- (Nitrate Ion)**:
- Nitrogen (N) has 7 electrons.
- Each Oxygen (O) has 8 electrons, and there are 3 Oxygen atoms.
- Therefore, the total number of electrons from Oxygen is: 8 * 3 = 24.
- The ion has a -1 charge, which means there is 1 extra electron.
- Total electrons = 7 (N) + 24 (O) + 1 (extra) = 32 electrons.
3. **SO3^2- (Sulfite Ion)**:
- Sulfur (S) has 16 electrons.
- Each Oxygen (O) has 8 electrons, and there are 3 Oxygen atoms.
- Therefore, the total number of electrons from Oxygen is: 8 * 3 = 24.
- The ion has a -2 charge, which means there are 2 extra electrons.
- Total electrons = 16 (S) + 24 (O) + 2 (extra) = 42 electrons.
4. **BO3^3- (Boron Trioxide Ion)**:
- Boron (B) has 5 electrons.
- Each Oxygen (O) has 8 electrons, and there are 3 Oxygen atoms.
- Therefore, the total number of electrons from Oxygen is: 8 * 3 = 24.
- The ion has a -3 charge, which means there are 3 extra electrons.
- Total electrons = 5 (B) + 24 (O) + 3 (extra) = 32 electrons.
Now, let's summarize the total number of electrons for each ion:
- CO3^2-: 32 electrons
- NO3^-: 32 electrons
- SO3^2-: 42 electrons
- BO3^3-: 32 electrons
From our calculations, we can see that CO3^2-, NO3^-, and BO3^3- all have 32 electrons, while SO3^2- has 42 electrons. Therefore, SO3^2- is not isoelectronic with the other three ions.
**Final Answer**: SO3^2- is not isoelectronic with the other three ions.
