The novel phenomenon of radioactivity was a promising field of research for many scientists at the beginning of the 20th century, including Ernest Rutherford (1871-1937). He was a New Zealand physicist and was awarded the Nobel Prize in Chemistry in 1908 "for his investigations into the decay of the elements and the chemistry of radioactive substances". Like many scientists at the time, he also wanted to find out how atoms are constructed.

From 1907, he worked as a professor at the University of Manchester and, together with his colleagues, investigated the properties of a certain part of radioactive radiation. This part is called α-radiation. It consists of two positively charged helium atoms, the α particles. They can penetrate thin layers of other materials. In 1908, his colleague Hans Geiger discovered that a narrow beam of α particles appears to fan out when it hits or penetrates a thin gold foil. The scattering that Geiger was able to determine was in the range of approximately one degree. Rutherford then entrusted Geiger and another young colleague, Ernest Marsden, with the task of investigating this scattering in more detail. Rutherford wanted to find out whether they could also be backscattered. But he didn't think it was possible.

Geiger and Marsden therefore designed an experiment to investigate whether the α particles could be scattered by a thin metal foil by more than just one degree. In the years from 1908 to 1913, they were able to show through several extensive experiments that α-particles are scattered more strongly by matter than was generally assumed. You can see one of the most important experiments in the following animation.

In 1911, Rutherford himself had developed a formula that could describe the scattering of α-particles, but it was based on some assumptions that had not been proven.

However, as Rutherford had only derived his formula theoretically, Geiger and Marsden wanted to confirm it experimentally. With the experiment you saw in the animation, Rutherford's colleagues were able to confirm the validity of the formula. The experiment is generally known as Rutherford's scattering experiment.

Looking back, Rutherford himself described the research of his working group and the conclusions he was able to draw from the experimental data about the structure of atoms.