Atomic structure.

... AS CHEMISTRY MODULE 1 ATOMIC STRUCTURE Easy Stuff * Matter is made up of atoms * All atoms of one element are of the same kind. * A compound contains atoms of two or more elements combined in fixed proportions. * Atoms are very small * Atoms are composed of sub-atomic particles; protons, neutrons and electrons The History The electron The electron was the first particle to be discovered by J J Thomson, who was looking into passing an electric current through gases. At the positive end of the tube a glow was visible. This glow could be deflected by both electric and magnetic fields, suggesting that there were rays of negative particles travelling from the cathode to the anode. These particles are obviously electrons. Thomson went on to suggest that atoms were like plum puddings with negative electrons embedded in a sphere of positive charge like the currants in a plum pudding. This was disproved by the Geiger-Marsden experiment, which

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