How did the discovery of isotopes contradict Dalton's atomic theory ?

Explanation

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

1. **Understanding Dalton's Atomic Theory**:
- Dalton's atomic theory, proposed in the early 19th century, states that all atoms of a given element are identical in mass and properties. This means that if you have a sample of hydrogen, all hydrogen atoms should have the same mass.

2. **Introduction to Isotopes**:
- Isotopes are variants of a particular chemical element that have the same number of protons but different numbers of neutrons. This results in different atomic masses for these isotopes.

...