Here's why:

* Protons: Hydrogen has 1 proton. The number of protons defines the element.

* Neutrons: The most common form of hydrogen (protium) has 0 neutrons. There are also isotopes of hydrogen like deuterium (1 neutron) and tritium (2 neutrons).

* Electrons: Hydrogen has 1 electron to balance the positive charge of the proton.

Let me know if you have any more questions about hydrogen or other elements!