Here's why:

* Hydrogen's Simplest Form: The most common form of hydrogen (hydrogen-1 or protium) consists of only one proton and one electron.

* Isotopes: There are other isotopes of hydrogen (deuterium and tritium) that contain neutrons.

* Deuterium has one proton, one neutron, and one electron.

* Tritium has one proton, two neutrons, and one electron.

Let me know if you have any other questions!