![]() ![]() ![]() In 1869, Dmitri Mendeleev created the first version of the periodic table of elementsof all known elements and predicted several new elements to complete the table. It was later shown that the glow was produced by cathode rays.ĭmitri Ivanovich Mendeleev was a Russian chemist and inventor. Plucker found that the electric discharge caused a fluorescent glow to form on the glass walls of the vacuum tube (cathode ray tube). This became the basis of theįaraday discovered that when the same amount of electricity is passed through different electrolytes, the mass of substance liberated/deposited at the electrodes is directly proportional to their equivalent weights.Įlectrolysis is a method of using a direct electric current (DC) to drive an otherwise non-spontaneous chemical reactionĮlectrolysis is the passage of a direct electric current through an ionic substance that is either molten or dissolved in a suitable solvent, resulting in chemical reactions at the electrodes and separation of materials. In 1832, Michael Faraday reported that the quantity of elements separated by passing an electric current through a molten or dissolved salt is proportional to the quantity of electric charge passed through the circuit. In chemical reactions, atoms are combined, separated, or rearranged.Atoms of different elements combine in simple whole-number ratios to form chemical compounds.Atoms cannot be subdivided, created, or destroyed.Atoms of a given element are identical in size, mass, and other properties atoms of different elements differ in size, mass, and other properties.Elements are made of extremely small particles called atoms.In 1803, John Dalton Proposed an "atomic theory".įive main points of Dalton's atomic theory: John Dalton was an English chemist, meteorologist and physicist. In 1704, Sir Isaac Newton, an English physicist and mathematician proposed a mechanical universe with small, solid masses in motion. He coined the term átomos, which means "uncuttable" or "the smallest indivisible particle of matter" in greek. Democritus (400 B.C.)Democritus proposed that matter was composed of tiny indivisible particles. ![]()
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