Write the trend of variation in atomic and ionic radii among the alkali metals.

Explanation

To understand the trend of variation in atomic and ionic radii among the alkali metals, we will analyze the group of alkali metals, which includes lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).

### Step-by-Step Solution:

1. **Identify the Alkali Metals**:
The alkali metals are located in Group 1 of the periodic table. The elements in this group are:
- Lithium (Li)
- Sodium (Na)
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