Atomic Model

Timeline created by monitonga
  • Dalton's Model

    1) All matter is made of atoms. Atoms are indivisible and indestructible. 2) All atoms of a given element are identical in mass and properties 3) Compounds are formed by a combination of two or more different kinds of atoms. 4) A chemical reaction is a rearrangement of atoms. 1803 John Dalton pictures atoms as timy, indestructive particles, with no internal stucture.
  • Thomas Model

    1897 J.J Thomas, a British Scientist, discovers the electron. The later leads to his "plumpudding" model. He pictures electrons embedded in a sphere of positive electrical charge.
    He was the first to suggest that the fundamental unit was over 1000 times smaller than an atom, suggesting the subatomic particles now known as electrons.Thomson made his suggestion on 30 April 1897 following his discovery that Lenard rays could travel much further through air than expected for an atom-sized particle.
  • Hanataro Nagaoka

    1904 Hanataro Nagaoka, a Japenese Physicist, suggests that an atom has a central nucleus. Electrons move in orbits like the rings around saturn.Nagaoka rejected Thomson's model on the ground that opposite charges are impenetrable. He proposed an alternative model in which a positively charged center is surrounded by a number of revolving electrons, in the manner of Saturn and its rings.
  • Ernest Rutherford

    Rutherford finds that atom has a small, dense, positively charged nucleus. Electrons move around the nucleus. This model suggested that most of the mass of the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space. Rutherford came to this conclusion following the results of his famous gold foil experiment.
  • Niels Bohr

    1913 in Niels Bohr's model, the electron moves in a circular orbit at fixed distances from the nucleus. Bohr depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus.As a theory, it can be derived as a first-order approximation of the hydrogen atom using the broader and much more accurate quantum mechanics, and thus may be considered to be an obsolete scientific theory.
  • Louis de Brogile

    1923 Louis proposes that moving particles like electrons have some properties of waves. Within a few years, experimental evidence supports the idea.He believed that electrons can act like both particles and waves, just like light. He also said that waves produced by electrons contained in the orbit around the nucleus, set up a standing wave of a certain energy, frequency, and wavelength. He discovered that electrons can act like waves.
  • Erwin Schrodinger

    1926 Schrodinger develops mathematical equations to describe the motion of electrons in atoms. His work leads to the electron cloud model.
  • James Chadwick

    1932 Chadwick, an English physicist, confirms the existence of neutrons, which have no charge. Atomic nuclei contain neutrons and positively charged protons. He believed that electrons can act like both particles and waves, just like light. He also said that waves produced by electrons contained in the orbit around the nucleus, set up a standing wave of a certain energy, frequency, and wavelength.