Beryllium Atomic number 4 so
Atomic number = Proton number
so P = 4
Electron = Proton Number
so E = 4
Neutron = Atomic mass - Atomic number
= 9 - 4
= 5
Note : Atomic mass find from Periodic table
Energy Level = 2 because of 2 orbitals
Hope this Help
Let me know if you have any question
