Define isotopes why do isotopes have same atomic number but differente mass numbers? Explain with the help an example.

Explanation

### Step-by-Step Text Solution:

**Step 1: Define Isotopes**
Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons. This means that isotopes of an element have the same atomic number but different mass numbers.

**Step 2: Explain Atomic Number and Mass Number**
- The atomic number (Z) of an element is the number of protons in the nucleus of an atom. It defines the element and determines its position in the periodic table.
- The mass number (A) is the total number of protons and neutrons in the nucleus. Since isotopes have the same number of protons (same atomic number), they differ in the number of neutrons, leading to different mass numbers.
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