Atomic Model

By sippelar
  • 500 BCE

    The Alchemists

    The Alchemists
    Theory: all metals are composed of mercury and sulfur & possible to change base metals into gold
  • 427 BCE

    Plato

    Plato
    introduced Atomic Theory; geometric forms serve as atoms.
    atoms broke down mathematically into triangles. The form elements had the following shape: fire (tetrahedron), air (octahedron), water (icosahedron), earth (cube). Plato first proposed that the planets followed perfect circular orbits around the Earth. This idea branched off and later developed the first Solar System.
  • 400 BCE

    Democritus

    Democritus
    Theory: everything is composed of atoms
    atoms are: physically, but not geometrically, indivisible; between atoms, there lies empty space; atoms are indestructible, and always will be in motion.
  • 340 BCE

    Aristotle

    Aristotle
    Theory: materials on Earth were not made of atoms, but of the four elements, Earth, Fire, Water, and Air All substances were made of small amounts of these four elements of matter.

  • Robert Boyle

    Robert Boyle
    helped develop definition of an element:( any substance that can be broken into 2 or more substances is not an element)
    * contribution to scientific theory;The Sceptical Chymist. Boyle addressed the concept of elements, rejecting doctrines of both Aristotle and Paracelsus.

  • Lavoisier

    Lavoisier
    total mass of products and reactants in a chemical reactions is always the same-led to theory of law of conservation of mass

  • John Dalton

    John Dalton
    theory: all matter composed of atoms; indivisible and indestructible building blocks.
    all atoms of an element are identical
    different elements have atoms of differing size and mass
    One of Daltons theories is the Solid Sphere of "Billiard Ball" Model. In tis theory, he thought atoms were the smallest particles of matter, he envisioned them as solid, hard spheres,

  • Dmitri Mendeleev

    Dmitri Mendeleev
    created periodic table

  • The Curies

    The Curies
    discovered the strongly radioactive elements polonium and radium

  • J.J. Thomson

    J.J. Thomson
    discovery of electron
    proposed the plum pudding model of the atom, which had negatively-charged electrons embedded within a positively-charged "soup."

  • Albert Einstein

    Albert Einstein
    mathematically proved the existence of atoms
    Atomic theory: any liquid is made up of molecules

  • Robert Millikan

    Robert Millikan
    succeeded in precisely determining the magnitude of the electron's charge

  • Ernest Rutherford

    Ernest Rutherford
    postulated the nuclear structure of the atom
    discovered alpha and beta rays
    proposed the laws of radioactive decay
    received the Nobel Prize in Chemistry in 1908

  • Neils Bohr

    Neils Bohr
    Theory of the Hydrogen Atom: based on quantum theory; energy is transferred only in certain well defined quantities.
    Electrons should move around nucleus only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted.

  • Henry G. J. Moseley

    Henry G. J. Moseley
    used self-built equipment to prove that every element's identity is uniquely determined by the number of protons it has which revealed the true basis of the periodic table
    helped him predict the existence of four new chemical elements, all of which were found

  • Werner Heisenberg

    Werner Heisenberg
    theory of quantum mechanics
    & discovering the uncertainty principle, which states that a particle's position and momentum cannot both be known exactly creator of Electron Cloud Model. The model is a way to help visualize the most probable position of electrons in an atom