Which of these element pairs possess nearly the same atomic radius?

Options

A. Fe, Co
B. Te, I
C. N, O
D. All of these

Answer

To determine which pairs of elements possess nearly the same atomic radius, we can analyze the atomic structure of each pair and evaluate the factors affecting atomic size. Here’s a step-by-step solution:

### Step 1: Analyze the First Pair - Iron (Fe) and Cobalt (Co)
- **Atomic Numbers**: Iron (Fe) has an atomic number of 26, and Cobalt (Co) has an atomic number of 27.
- **Electron Configuration**:
- Fe: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶
- Co: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁷
- **Analysis**: Both elements have the same number of electron shells (n=4) and their d-electrons are in the same principal energy level. The effective nuclear charge is similar, and the d-electron repulsion balances out, leading to similar atomic radii.

### Step 2: Analyze the Second Pair - Tellurium (Te) and Iodine (I)
- **Atomic Numbers**: Tellurium (Te) has an atomic number of 52, and Iodine (I) has an atomic number of 53.
- **Electron Configuration**:
- Te: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴
- I: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵
- **Analysis**: Both elements have the same number of electron shells (n=5), and the addition of one electron in Iodine does not significantly affect the atomic radius. The effective nuclear charge remains similar, resulting in comparable atomic sizes.

### Step 3: Analyze the Third Pair - Nitrogen (N) and Oxygen (O)
- **Atomic Numbers**: Nitrogen (N) has an atomic number of 7, and Oxygen (O) has an atomic number of 8.
- **Electron Configuration**:
- N: 1s² 2s² 2p³
- O: 1s² 2s² 2p⁴
- **Analysis**: Both elements have the same number of electron shells (n=2), and the increase in the number of electrons in the p-orbital does not significantly change the atomic radius. The effective nuclear charge is similar, leading to comparable atomic sizes.

### Conclusion
Based on the analysis:
- The pairs **Iron and Cobalt**, **Tellurium and Iodine**, and **Nitrogen and Oxygen** all possess nearly the same atomic radius.