Nucleus

created my elisabeth mcdonnell

Main Idea

The nucleus is the small, dense region consisting of protons and neutrons at the center of an atom. This nucleus accounts for most (if not all) of the weight in an atom but only a small fraction of its volume. This nucleus is made up of protons and neutrons densely smushed together, and surroudning this dense mass is a space which electrons float and orbit in. The nucleus is particularly critical in identifying elements, which are identified by the number of protons in the nucleus.

Please follow the following link in order to view how atoms move. The dense ball in the middle is the nucleus and the revolving orbits represent the paths of the electrons

http://bestanimations.com/Science/Chemistry/Chemistry.html

History

The nucleus was discovered in 1911, because Rutheford wanted to test Thomson's "plum pudding model" of the atom. In the plum pudding model, Thomson suggested that an atom had negative electrons scattered all around a positive charge, or group of them. Ernest Rutherford did an experiment that involved the deflection of alpha particles directed at a thin sheet of metal foil. He thought if this "Plum" model was correct then the positively charged alpha particles would pass through the foil with very little trouble, as the foil should act as electrically neutral. To his surprise, many of the particles were deflected at very crazy and bizarre 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. This basically meant the whole plum pudding model was a giant lie 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 concentrated point was identifies, and viola- the nucleus was born!!