Atomic Structure Timeline

By 15gracel
  • 460 BCE

    Theory of the Existence of Atoms

    Democritus, of Greece, theorized that everything is made of atoms, which are indestructible and too small to see, and differ in size, shape, and arrangement.
  • 399 BCE

    Trial and Execution of Socrates

  • 44 BCE

    Julius Caesar Assassinated

  • 31 BCE

    Octavian Becomes First Dictator of Roman Empire

  • 4 BCE

    Jesus Christ is Born

  • 33

    Jesus is Crucified

  • 285

    Emperor Diocletian Divides the Roman Empire to create the Byzantine Empire

  • Jan 1, 632

    Foundation of Islam

  • Oct 1, 1347

    Arrival of the Black Death in Europe

  • Declaration of Independence

  • French Revolution Begins

  • The Atomic Theory

    John Dalton, of the UK, theorized that all matter is made of atoms, which are indivisible. He suggested that atoms of a given element are identical in mass and properties, compounds are combinations of two or more different types of atoms, and a chemical reaction is a rearrangement of atoms.

  • Establishment of the Mormon Church

  • Charles Darwin Begins His Journey

  • Final Installment of Oliver Twist

  • First Wagon Train Leaves Missouri for Oregon

  • Irish Famine Begins

  • The Periodic Table

    Dmitri Mendeleev, of Russia, organized the a table of all known elements by each element’s atomic weights, which tried to make sense of the relationships between all of the elements. The table later became organized by atomic number (number of protons) as suggested by British Henry Moseley in 1914.

  • Eruption of Krakatoa in Indonesia Leads to a Year Without Summer

  • The Existence of Charged Subatomic Particles (within the atom)

    JJ Thomson, of England, discovered the existence of electrons and theorized that there must be the particles that are positively charged, because atoms have a neutral charge, not a negative charge. Both these particles were examples of subatomic particles.

  • The Discovery of the Electron

    J.J. Thomson, of England, connected a cathode ray tube to electricity and saw that he could see particles moving around, which were attracted to the positive end of a magnet- meaning the particles were negatively charged. This led to the creation of his Plum Pudding model of an atom, where electrons were randomly scattered throughout.

  • Hawaii Becomes a US Territory

  • The Discovery of the Nucleus

    Ernest Rutherford, of New Zealand, created his Gold Foil experiment where he shot positive particles at a screen and saw some scattering of the particles. He then realized this scattering was because some particles were hitting a positively charged part of the atom, the nucleus, and were being repelled by its positive charge.

  • Sinking of the Titanic

  • The Structure of the Electron Cloud into Levels

    Niels Bohr, of Denmark, theorized that electrons traveled in orbits around the nucleus, with the outer orbits determining the atom’s chemical properties.

  • World War I Begins

  • The Discovery of the Proton

    Ernest Rutherford, of New Zealand, bombarded hydrogen gas with particles to knock the nuclei out of the atoms, and realized that nitrogen could be made into oxygen by bombarding it with particles, with a second product that looked like the hydrogen nuclei, meaning that hydrogen nuclei were a piece of all nuclei - a new particle, the proton.

  • The Discovery of Isotopes

    Francis Aston, of England, invented the mass spectograph, which electromagnetically separated different isotopes of elements based on their slightly different masses. This provided proof of the existence of different isotopes of elements.

  • The Quantum Mechanical Model

    Erwin Schrödinger, of Austria, theorized at the University of Zurich that electrons could be treated as waves of matter, which allows measurement of electrons’ energy levels. Schrödinger created a wave equation for this, known as the Quantum Mechanical Model.

  • Grandmother's Birth Date

  • The Discovery of the Neutron

    James Chadwick, of England, shot radiation at hydrogen-containing paraffin and observed that the paraffin's protons were scattered by radiation particles similarly sized to protons-- neutrons.

  • World War II Begins

  • My Mom's Birth Date

  • The Existence of Subnuclear Particles

    Murray Gell-Mann, of the United States, theorized the Eightfold Way theory at the California Institute of Technology, which made sense of about 100 different particles in the nucleus. The theory suggested that all of the particles are made of smaller particles, called quarks.

  • My Birth Date

  • Date I Started High School