To which the following atom, the attachment of electron is most difficult ?

Options

A. Radon
B. Nitrogen
C. Oxygen
D. Radius

Answer

To determine which atom has the most difficulty in attaching an electron, we need to consider the electronic configurations of the atoms in question. Atoms that have fully filled or half-filled orbitals are generally more stable and less likely to gain additional electrons.

### Step-by-Step Solution:

1. **Identify the Atoms**: First, we need to identify the atoms given in the question. For this example, let's assume we are considering noble gases and other elements.

2. **Understand Electron Affinity**: Electron affinity is the energy change that occurs when an electron is added to a neutral atom. Atoms with a stable electronic configuration (like noble gases) have a low tendency to gain electrons because they are already stable.

3. **Analyze Noble Gases**: Noble gases, such as helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn), have completely filled outer electron shells. This makes them highly stable and unreactive.

4. **Focus on Radon**: Among the noble gases, radon (Rn) has the highest atomic number (86) and is the heaviest. Its electronic configuration is [Xe] 4f14 5d10 6s2 6p6, which is completely filled.

5. **Conclusion**: Since radon has a fully filled electronic configuration, it is energetically unfavorable for radon to gain an additional electron. Therefore, the attachment of an electron to radon is the most difficult compared to other atoms.

### Final Answer:
The atom to which the attachment of an electron is most difficult is **Radon (Rn)**.

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