atoms discovery

Electron - Discharge Tube experiments These experiments were conducted in detail by J.J. Thomson and he studied the passage of electricity through gases at extremely low pressure in a cylindrical glass tube. It was discovered that at extremely low pressure, gases become conductors of e..

The whole mass of an atom is due to the nucleus, which means that the nucleus must contain protons equal to the mass of the atom. As the number of protons is equal to the atomic number, the atomic mass should be equal to the atomic number. But for ..

Production of anode rays - Since the atom is electrically neutral there must be positively charged particles present in the atom to neutralize the negative charges of the electrons. Goldstein experimentally proved the existence of protons in the atom..

The discovery of the phenomenon of radioactivity was purely accidental. In 1896, Henry Becquerel, a French scientist accidentally found that in presence of salt of uranium, photographic plates got heavily fogged even though they were wrapped in opaque paper. He concluded that the uranium ..

Production of cathode rays - In 1885, Sir William Crookes carried out a series of investigations into the behaviour of metals heated in a vacuum. The experiment of Crookes and others showed that a heated cathode produced a stream of radiation, which could cause gases at low pressure to glow and whi..

Discovery of Radioactivity and Nature of Radiations - In 1896, the phenomenon of radioactivity was accidentally discovered by French scientist Henri Becquerel. He was performing experiments with uranium compounds. He accidentally placed a crystal of potassium uranyl sulphate over photogra..

Ernest Rutherford, an energetic New Zealander working in England, was studying the properties of particles spontaneously emitted by radioactive substances. Of particular interest was a positively charged, relatively heavy emission named alpha particle. Quantities of such particles are emitted by c..

Atoms and Nuclei..

Summary Atom is the smallest particle of an element, which maintains its identity throughout chemical and physical changes. Atoms are made up of three fundamental particles: electrons, protons and neutrons. Discharge tube experiments by William Crookes and J.J. Thomso..

. He was awarded the Nobel Prize in 1908. The famous words of Rutherford on completing the alpha rays scattering experiment were: 'It was quite the most incredible event that has ever happened to me in life. It was almost as if you fired a 15 inch shell into a piece of tissue paper and it came back..