Rutherford concluded that since most alpha particles passed straight through, atoms must be mostly empty space. Most of them did, but a puzzling subset of them were either deflected at large angles by the atoms in the foil or bounced straight back from it. If Thomson’s plum pudding model were correct, the alpha particles would have whizzed through the sheet undeflected. The experiments involved firing a narrow beam of ‘alpha particles’ emitted from a decaying radioactive source at a very thin sheet of gold foil. In 1909, Ernest Rutherford oversaw the ‘Geiger-Marsden experiments’. It wasn’t long however until a new ‘nuclear’ model was announced a few years later… The Geiger-Marsden Experiments He visualized materials and substances as being made up of countless small spheres, each sphere having a positive charge spread uniformly around its volume and being distributed with electrons. His work stands out as the very first attempt to represent the atomic structure of matter. His model attempted to explain the two known properties of atoms at the time: 1) the negative charge of electrons and 2) that atoms have zero net charge, meaning the positive and negative components must balance out somehow. Since his work predated the ‘atomic nucleus’, he represented the atom as negatively charged “plums” embedded in a positively charged “pudding”. Thomson outlined his ‘Plum Pudding Model’ of the atom in 1904 a few years after discovering the electron in 1897. The Plum Pudding Atomic ModelĮnglish Physicist J.J. A giant leap forward, but his theory failed to predict the existence of subatomic particles such as protons, neutrons, and electrons.

He hypothesized that matter is made up of tiny, indivisible particles called ‘atoms’ which could form molecules and be rearranged, combined, or separated during chemical reactions. In 1803, English chemist John Dalton published his atomic theory which revolutionized the field of chemistry. Once we have explored the dramatic shifts in how atoms and subatomic particles have been envisaged over time, we will discover what the building blocks of our universe look like when examined under a quantum lens. In this tile we will embark on a whistle-stop tour of the most influential atomic models which have been developed, and the experimental evidence that inspired them. In the same way we have refined our understanding of light over the years, scientists have embarked on a similar journey with the nature of matter and the atoms that comprise it.

Erwin schrodinger atomic theory