Which of the following is the correct order of atomic radii

Options

A. `F lt Li lt Na lt K`
B. `F gt K gt Na gt Li`
C. `Na gt K gt F gt Li`
D. `Li gt Na gt K gt F`

Explanation

To determine the correct order of atomic radii among the given elements, we need to understand how atomic radii change across periods and down groups in the periodic table.

### Step-by-Step Solution:

1. **Understanding Atomic Radii Trends**:
- Atomic radii generally **increase** as you move **down a group** in the periodic table. This is because additional electron shells are added, which increases the distance between the nucleus and the outermost electrons.
- Atomic radii generally **decrease** as you move **from left to right** across a period. This is due to the increase in nuclear charge, which pulls the electrons closer to the nucleus.

2. **Identifying the Elements**:
- The elements mentioned are: **Hydrogen (H)**, **Lithium (Li)**, **Sodium (Na)**, **Potassium (K)**, **Rubidium (Rb)**, and **Fluorine (F)**.
- We need to focus on the order of atomic radii among **Lithium (Li)**, **Sodium (Na)**, **Potassium (K)**, and **Fluorine (F)**.

3. **Analyzing the Group and Period**:
- **Lithium (Li)**, **Sodium (Na)**, and **Potassium (K)** are all in Group 1 (alkali metals) and will show an increasing trend in atomic radii as we go down the group:
- **Li < Na < K**
- **Fluorine (F)** is in Period 2 and is located to the right of Lithium. Therefore, it will have a smaller atomic radius compared to Lithium:
- **F < Li**

4. **Combining the Information**:
- From the trends, we can conclude the order of atomic radii from smallest to largest:
- **Fluorine (F) < Lithium (Li) < Sodium (Na) < Potassium (K)**

5. **Final Order**:
- Therefore, the correct order of atomic radii is:
- **F < Li < Na < K**

### Conclusion:
The correct order of atomic radii is **Fluorine < Lithium < Sodium < Potassium**.