The J. J. Thompson atomic model, also known as the "plum pudding model," was a proposed model of atomic structure where individual electrons were embedded in a cloud of positive charge. It was abandoned in favor of the modern model of a dense positively charged nucleus surrounded by a cloud of electrons. Sir Joseph John Thompson, the main proponent of this model, was also the first discoverer of electrons.
The J. J. Thompson atomic model was actually first proposed by Lord Kelvin, for whom the Kelvin absolute temperature scale is named, but Sir Thompson was its largest backer. He continued to be enthusiastic about it even after Lord Kelvin himself proposed alternate models. The model was disproved by the Rutherford gold foil experiment. In it, alpha radiation, which is actually composed of helium nuclei, was exposed to gold foil surrounded by a wall of zinc sulfide. The wall lit up whenever a helium nuclei hit it. It did not behave in a manner consistent with the J. J. Thompson model, and it had to be rejected in favor of the Rutherford model. The basic element of this model that is still accepted today is the existence of a small, dense nucleus. It was proposed by Ernest Rutherford after analysis of the experiment.Learn More
The smallest atom in the periodic table in terms of mass is hydrogen, which has only one proton and one electron. Hydrogen has no neutrons. The element has an atomic number of 1 and atomic weight of 1.00794, making it the smallest of all the elements.Full Answer >
Elements from the lanthanide series are used for petroleum production, lasers, magnets, projectors, X-ray screens and as a component of steel and magnesium alloys. The lanthanides are soft, highly reactive metals that burn easily and act as strong reducing agents.Full Answer >
Sodium oxide is a chemical compound with the formula Na2O. Its molar mass is 61.98 grams per mole. It is a white solid substance with a density of 2.27 grams per cubic centimeter. Its melting point is 2,070 degrees Fahrenheit, and its boiling point is 3,540 degrees Fahrenheit.Full Answer >
The atomic mass of aluminum is 26.981539 amu and the atomic number of aluminum is 13. This light, grey metal is able to resist corrosion which makes it ideal for many applications.Full Answer >