The Bohr Model for Beryllium (Be) has 4 protons in the nucleus due to the atomic number of Be being 4. The Mass number is 9 which means Beryllium needs 5 neutrons in the nucleus. (Mass number = protons + neutrons, 9 = 4 + n). Beryllium has four electrons to balance the four protons. The 4 electrons are arranged with 2 electrons in the first orbital and 2 electrons in the second orbital.