Roentgenium (Rg) is a synthetic element with the atomic number 111. Here's the breakdown of its subatomic particles:

* Protons: 111 (This defines its atomic number and its identity as roentgenium)

* Neutrons: This varies depending on the isotope of roentgenium. The most common isotope, Roentgenium-281, has 170 neutrons.

* Electrons: 111 (In a neutral atom, the number of electrons always matches the number of protons)