Atomic Theory Timeline

Timeline created by taylorhenderson18
  • 400

    Greek Atomic Theory: Democritus-everything is composed of atoms

    Democritus: everything is composed of atoms
  • Period:
    400
    to

    Atomic Theory TImeline

  • Law of definite composition

    A compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound.
  • Law of multiple proportions

    Applies to different compounds made from the same elements.
    Mass ratio for one of the elements that combines with a fixed mass of the other element can be expressed in small whole numbers.
  • Antione Lavoisier

    Conservation of mass-total mass of a product of a chemical reaction is always same as total mass.Total mass of the products is the same as the sum of the masses of the reactants. Matter cannot be neither created nor destroyed, just rearranged.
  • Law of Conservation of Mass

    Matter cannot disappear it can only be rearranged, at high speeds mass changes to energy
  • Joseph Louis Proust

    created the law of constant composition
  • Dalton's Atomic Theory

    Oxygen and Carbon combined to make 2 compounds. ALL matter is made of invisible/indestructable atoms. Atoms of a given element are identical in their physical and chemical properties. Atoms of different elements have different physical/chemical properties. Atoms of different elements combine in simple, whole-number ratios to form chemical compounds. Atoms cannot be subdivided, created, or destroyed when they are combined, separated, or rearranged in chemical reactions.
  • John Dalton

    Recorded the 1st tables of relative atomic mass and the atomic number
  • Law of Definite Proportions

    If formula AB is constant then the weight ratio will stay the same
  • Dmitri Mendeleev

    Created the periodic table and the list of elements
  • Eugene Goldstein

    Investigated the X-rays and discovered the cathode rays
  • Erwin Schrodinger

    Created the Schrodinger equation that is used to describe the behavior of electrons in atoms
  • Cathode Ray Tube

    2 positive lead atoms connected into a neon tube will make it light up, electric makes light
  • J.J Thompson

    Discovered that cathode rays (applied the voltage across glass tubes which was sealed with various gases) are small steams of atoms and an electron has a negative charge. Implied that the ray was not a consequence of the gas, but rather an entity in and of itself.
  • Plum Pudding Model

    there has to be a positive and a negative charge to balance out the atom, atoms are neutral
  • Marie Curie

    Discovered the radioactive elements
  • Rutherford Model

    Model of nucleus and electrons, discovered that the nucleus is in the center and the electrons orbit it
  • Ernest Rutherford

    Discovered/studied alpha particles and discovered the positively charged nucleus. There must be something within the atom that must be massive as the particles being shot at it.
  • Robert Milikan

    Made the oil drop experiment which made electron have an electric charge
  • Bohr Planetary Model

    He thought that electrons only orbit in one direction, called stationary orbits. Electrons/planets in an atom can reside only in certain energy levels; the energy of an electron in an atom is quantized.
  • NIels Bohr

    Considered the term of stationary orbits for the electrons and that there is more than one level to orbit, also introduced the Electron cloud. "The electron in a hydrogen atom moves around the nucleus only in certain allowed circular orbits". Proposed that the energy of an electron in an atom is quantized.
  • Henry Mosdeley

    Numbered and ordered the elements
  • Quantam Mechanical Model

    Mathematical equation developed by Schrodinger, calculated where electrons are at any given moment
  • Gold Foil Experiment

    Showed that the nucleus is positive, and electrons orbit it
  • James Chadwick

    Found the neutron, and his discovery led to nuclear fission and the atomic bomb. The neutron is found in the nucleus with the proton. The mass of a neutron=mass of a proton. The neutron has no charge.
  • Lise Meitner

    FIrst discovered nuclear fission