Bohr's model of the atom has a positively charged nucleus surrounded by electrons,just like Rutherford's model. However,Bohr suggested that the electrons in an atom are arranged in orbits or shells around the nucleus of the atom.Each shell is numbered 1,2,3,4 and so on,going outwards from the nucleus. The shell number is also known as the quantumnumber. This number must be an inteqer.