Atomic Theories

Timeline created by Tyra Meredith
  • Isaac Newton

    Isaac Newton
    English physicist and mathematician who was born into a poor farming family. Luckily for humanity, Newton was not a good farmer, and was sent to Cambridge to study to become a preacher. At Cambridge, Newton studied mathematics, being especially strongly influenced by Euclid, although he was also influenced by Baconian and Cartesian philosophies. Proposed a mechanical universe with small solid masses in motion.
  • Dalton's Atomic Theory

    Dalton's Atomic Theory
    ~Elements are made of extremely small particles called atoms.
    ~Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.
    ~Atoms cannot be subdivided, created, or destroyed.
    ~Atoms of different elements combine in simple whole-number ratios to form chemical compounds.
    ~In chemical reactions, atoms are combined, separated, or rearranged.
  • J.J Thompson's atomic theory

    J.J Thompson's atomic theory
    The plum pudding model of the atom. This model was conceived after Thomson's discovery of the electron as a discrete particle, but before it was understood that the atom had a central nucleus. In this model, the atom is a ball of positive charge -- the pudding -- in which the electrons -- the plums -- are located. The electrons rotate in defined circular paths within the positive blob that makes up the majority of the atom.
  • Rutherfords Atomic Theory

    Rutherfords Atomic Theory
    Discovered that most of the mass and positive charge of an atom is concentrated in a very small fraction of its volume, which he assumed to be at the very center.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.
  • Frederick Soddy Discovery

    Frederick Soddy Discovery
    Discovered that there appeared to be more than one element at each position on the periodic table.The term isotope was coined by Margaret Todd as a suitable name for these element.
  • Bohr's Atomic Theory

    Bohr's Atomic Theory
    CONSTANT ENERGY CONCEPT:
    Energy of an electron is constant in one of its allowed orbits. As long as an electron remains in its orbit, it neither absorbs nor radiates energy.
    CONCEPT OF ENERGY LEVELS:
    Electrons revolve around the nucleus of atom in circular orbits in which energy of electrons is constant. These circular paths are known as "energy levels" or "stationary states".
  • Werner Heisenberg

     Werner Heisenberg
    One of the greatest physicists of the twentieth century. He is best known as a founder of quantum mechanics, the new physics of the atomic world, and especially for the uncertainty principle in quantum theory. He is also known for his controversial role as a leader of Germany's nuclear fission research during World War II. Proposed Principle of Indeterminancy - you can not know both the position and velocity of a particle.
  • Atomic Bomb Discovery

    Atomic Bomb Discovery
    Leo Szilard the inventor of the atmoic bomb.On July 4, 1934 Leo Szilard filed a patent application for the atomic bomb In his application, Szilard described not only the basic concept of using neutron induced chain reactions to create explosions, but also the key concept of the critical mass. The patent was awarded to him - making Leo Szilard the legally recognized inventor of the atomic bomb.
  • Enrico Fermi

    Enrico Fermi
    He discovered new radioactive elements produced by neutron irradiation, and nuclear reactions brought about by slow neutrons.
    Fermi's momentous accomplishments caused him to be recognized as one of the great scientists of the 20th century.
  • Radiocarbon Dating Discovery

    Radiocarbon Dating Discovery
    One of the most frequent uses of radiocarbon dating is to estimate the age of organic remains from archaeological sites. The technique of radiocarbon dating was developed by Willard Libby and his colleagues at the University of Chicago in 1949. Libby estimated that the steady state radioactivity concentration of exchangeable carbon-14 would be about 14 disintegrations per minute (dpm) per gram.