The smallest and ultimate particle of an element is called ___________.

Explanation

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks for the smallest and ultimate particle of an element.

2. **Identifying the Term**: In chemistry, the term used to describe the smallest unit of an element is "atom".

3. **Definition of Atom**: An atom is the basic building block of matter and is the smallest unit of an element that retains the properties of that element.

4. **Conclusion**: Therefore, the answer to the question is "atom".

**Final Answer**: The smallest and ultimate particle of an element is called **atom**.

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