The scientist Niels Bohr improved Rutherford’s nuclear model. Bohr proposed a model that included a positively charged nucleus in the centre with electrons orbiting the nucleus in a similar way to how planets orbit the Sun.
Bohr’s model is often referred to as the planetary model.
The series of energy levels is at increasing distances from the nucleus. Each energy level holds a maximum number of electrons.
The idea that electrons orbit the nucleus became more accepted than the notion of a general cloud of electrons. This is because it supported the results of experiments by other scientists.
After further experiments, Ernest Rutherford confirmed that the positive charge in the nucleus is due to small particles known as protons.
Not long after, in 1932, James Chadwick provided evidence for particles in the nucleus with no charge. These are particles we now know as neutrons.
The discovery of the neutron led to an improved model of the atom: