GeigerMarsden

GeigerMarsden refers to the Geiger-Marsden experiment, also known as the Rutherford gold foil experiment. This pivotal experiment was conducted in 1909 by Hans Geiger and Ernest Marsden under the direction of Ernest Rutherford. Their primary objective was to probe the structure of the atom by observing the scattering of alpha particles when they were directed at a thin sheet of gold foil.

The prevailing atomic model at the time was J.J. Thomson's "plum pudding" model, which proposed that the atom was a diffuse sphere of positive charge with electrons embedded within it. Based on this model, the researchers expected the alpha particles, which are positively charged, to pass through the foil with minimal deflection.

However, the results of the experiment were surprising and led to a radical revision of atomic theory. While most alpha particles did pass through the gold foil as expected, a small fraction were deflected at large angles, and some even bounced back towards the source. Rutherford famously described this as being "as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you."

This unexpected scattering led Rutherford to propose his nuclear model of the atom in 1911. He concluded that the atom's positive charge and most of its mass were concentrated in a tiny, dense region at the center, which he termed the nucleus. The electrons, much lighter and negatively charged, were thought to orbit this nucleus. The Geiger-Marsden experiment provided the crucial experimental evidence that supported Rutherford's revolutionary nuclear model, fundamentally changing our understanding of atomic structure.