Why do elements with similar properties occur in the same group?

Explanation

**Step-by-Step Solution:**

1. **Understanding Valence Electrons:**
- Valence electrons are the electrons located in the outermost shell of an atom. They play a crucial role in determining how an element reacts chemically.

2. **Grouping of Elements:**
- The periodic table is organized into groups (columns). Elements that are in the same group have similar physical and chemical properties.

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