A Beryllium (Be) atom has the following subatomic particles:
- Protons: 4 (This is equal to the atomic number of beryllium, which is 4.)
- Neutrons: Typically 5 (The most common isotope of beryllium is Beryllium-9, which has 4 protons and 5 neutrons. You can calculate neutrons by subtracting the atomic number from the mass number: 9 - 4 = 5.)
- Electrons: 4 (In a neutral atom, the number of electrons is equal to the number of protons.)
So, a neutral beryllium atom has 4 protons, 5 neutrons, and 4 electrons.