Who invented plum pudding model

There were a small number of Greeks who had a different idea. They believed that if there was a piece of wood for example, it could be cut into smaller and smaller pieces until it ended up as a piece of wood that was so small it couldn't be cut anymore. The ancient Greek philosopher Demokritos BCE thought that matter was made up of millions of tiny, uncuttable pieces of that same matter.

This problem would be solved by Niels Bohr in discussed in Chapter Bohr suggested that instead of buzzing randomly around the nucleus, electrons inhabit orbits situated at a fixed distance away from the nucleus. Oppositely charged objects attract each other. The atom is mostly empty space. Electrons orbit around the center of the atom. The main difference between Bohr model and Rutherford model is that in Rutherford model, electrons can revolve in any orbit around the nucleus, whereas in Bohr model, electrons can revolve in a definite shell.

When an atom has an equal number of electrons and protons, it has an equal number of negative electric charges the electrons and positive electric charges the protons. The total electric charge of the atom is therefore zero and the atom is said to be neutral. Skip to content Science. Table of Contents. When voltage is applied across the electrodes, cathode rays are generated which take the form of a glowing patch of gas that stretches to the far end of the tube. Through experimentation, Thomson observed that these rays could be deflected by electric and magnetic fields.

Upon measuring the mass-to-charge ration of these particles, he discovered that they were 1ooo times smaller and times lighter than hydrogen.

This effectively disproved the notion that the hydrogen atom was the smallest unit of matter, and Thompson went further to suggest that atoms were divisible. To explain the overall charge of the atom, which consisted of both positive and negative charges, Thompson proposed a model whereby the negatively charged corpuscles were distributed in a uniform sea of positive charge.

And from this, the Plum Pudding Model was born, so named because it closely resembled the English desert that consists of plum cake and raisins. Unfortunately, subsequent experiments revealed a number of scientific problems with the model. Five years later, the model would be disproved by Hans Geiger and Ernest Marsden, who conducted a series of experiments using alpha particles and gold foil. However, they noted instead that while most shot straight through, some of them were scattered in various directions, with some going back in the direction of the source.

Since alpha particles are just helium nuclei which are positively charged this implied that the positive charge in the atom was not widely dispersed, but concentrated in a tiny volume.

In addition, the fact that those particles that were not deflected passed through unimpeded meant that these positive spaces were separated by vast gulfs of empty space. Instead, he proposed a model where the atom consisted of mostly empty space, with all its positive charge concentrated in its center in a very tiny volume, that was surrounded by a cloud of electrons.

This came to be known as the Rutherford Model of the atom. While Van den Broek suggested that the atomic number of an element is very similar to its nuclear charge, the latter proposed a Solar-System-like model of the atom, where a nucleus contains the atomic number of positive charge and is surrounded by an equal number of electrons in orbital shells aka.