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In 1803 Dalton discovered that oxygen combined with either one or two volumes of nitric oxide in closed vessels over water and this pioneering observation of integral multiple proportions provided important experimental evidence for his incipient atomic ideas. -
J.J. Thomson's experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. Thomson proposed the plum pudding model of the atom, which had negatively-charged electrons embedded within a positively-charged "soup." -
His theory (the Bohr atomic model) wove the new concept of quanta (or specific discrete energy values) into the electrodynamics of orbits, and ...
Subjects Of Study: Rutherford model atom r -
The Bohr model of the atom was proposed by Neil Bohr in 1915. It came into existence with the modification of Rutherford's model of an atom. Rutherford's model introduced the nuclear model of an atom, in which he explained that a nucleus (positively charged) is surrounded by negatively charged electrons. -
James Chadwick's contribution to the atomic model was his discovery of the neutron. The neutron is a neutrally charged subatomic particle that is about the same mass as the proton. Both protons and neutrons occupy the nucleus of the atom. Chadwick was able to discover the neutron and measure its mass.