Here's why:

* Atomic Structure: Atoms are made up of protons, neutrons, and electrons.

* Protons: Protons are positively charged particles found in the nucleus of an atom. They determine the element's atomic number.

* Hydrogen: Hydrogen has an atomic number of 1, meaning it has only one proton.

* Isotopes: While most hydrogen atoms have one proton and one electron, there are isotopes like deuterium (one proton, one neutron) and tritium (one proton, two neutrons). However, the most common form of hydrogen only has a single proton.