What Is the World Made Of?


Are atoms indivisible?

Thanks to the invention of the electric battery in 1800 by Alessandro Volta (17451827) chemists had a new tool to create reactions and isolate new elements. Sir Humphry Davy was one of the most active and isolated sodium, potassium, and calcium from their salts. But it was his assistant, Michael Faraday (1791-1867), who most contributed to the discovery that the atom was not indivisible. He found that the amount of charge needed to liberate an element from a solution was proportional to the mass of the element. In modern language the amount of charge was proportional to the number of atoms liberated. It took until 1881 for the import of this result to be realized when Hermann von Helmholtz (1821-1894) pointed out that if elements are composed of atoms, then electricity could be divided into portions that could be called atoms of electricity. George Johnstone Stoney named these atoms “electrons.” But what were they?


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