s- and p- Block element are collectively called ………… elements.

Explanation

**Step-by-Step Solution:**

1. **Identify the Blocks of Elements**: The s-block elements include groups 1 and 2 of the periodic table, while the p-block elements include groups 13 to 18.

2. **Understand the Term "Representative Elements"**: The s- and p-block elements are collectively referred to as "representative elements." This term is used because these elements exhibit a wide range of physical and chemical properties and are representative of the main group elements.

3. **Characteristics of Representative Elements**:
- They have varying valence electron configurations.
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