Why the elements of second row (first short period) show a number of differences in properties from other members of their respective families ?

Explanation

To understand why the elements of the second row (first short period) exhibit a number of differences in properties from other members of their respective families, we can break down the explanation into several key points:

### Step-by-Step Solution:

1. **Atomic Size**:
- The elements in the second row of the periodic table, such as lithium (Li) and beryllium (Be), have smaller atomic sizes compared to their counterparts in the same group (like sodium (Na) and magnesium (Mg)). This smaller size affects their physical and chemical properties, making them behave differently.

**Hint**: Remember that atomic size influences the distance between the nucleus and the valence electrons, affecting reactivity.
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