* Hydrogen-1 (¹H) has no neutrons. It consists of one proton and one electron. This is the most common form of hydrogen, making up about 99.98% of all hydrogen atoms.
* Hydrogen-2 (²H or D), also known as deuterium, has one neutron in addition to its one proton and one electron. This makes it twice as heavy as hydrogen-1.
Here's a table summarizing the key differences:
| Isotope | Number of Protons | Number of Neutrons | Atomic Mass | Abundance |
|---|---|---|---|---|
| Hydrogen-1 (¹H) | 1 | 0 | 1 | 99.98% |
| Hydrogen-2 (²H or D) | 1 | 1 | 2 | 0.02% |
While both isotopes have the same chemical properties, the extra neutron in deuterium gives it slightly different physical properties, such as a higher boiling point and density.
