j.j. thomson created the plum pudding model of the atom.
who created the plum pudding model of the atom?
j.j. thomson
the nucleus was discovered in 1911, as a result of ernest rutherford's efforts to test thomson's "plum pudding model" of the atom. the electron had already been discovered earlier by j.j. thomson himself. knowing that atoms are electrically neutral, thomson postulated that there must be a positive charge as well. in his plum pudding model, thomson suggested that an atom consisted of negative electrons randomly scattered within a sphere of positive charge. ernest rutherford later devised an experiment with his research partner hans geiger and with help of ernest marsden, that involved the deflection of alpha particles (helium nuclei) directed at a thin sheet of metal foil. he reasoned that if thomson's model were correct, the positively charged alpha particles would easily pass through the foil with very little deviation in their paths, as the foil should act as electrically neutral if the negative and positive charges are so intimately mixed as to make it appear neutral. to his surprise, many of the particles were deflected at very large angles. because the mass of an alpha particle is about 8000 times that of an electron, it became apparent that a very strong force must be present if it could deflect the massive and fast moving alpha particles. he realized that the plum pudding model could not be accurate and that the deflections of the alpha particles could only be explained if the positive and negative charges were separated from each other and that the mass of the atom was a concentrated point of positive charge. this justified the idea of a nuclear atom with a dense center of positive charge and mass.
atomic nucleus
plum pudding model









































the plum pudding model is one of several historical scientific models of the atom. first proposed by j. j. thomson in 1904 soon after the discovery of the electron, but before the discovery of the atomic nucleus, the model tried to explain two properties of atoms then known: that electrons are negatively-charged particles and that atoms have no net electric charge. the plum pudding model has electrons surrounded by a volume of positive charge, like negatively-charged "plums" embedded in a positively-charged "pudding".









































section::::overview.
plum pudding model