science flashcards

  1. Democritus
    • - a greek philiosphoer in 440 B.C
    • - Came up with the Concept of the Atom
    • - HE said that atoms were small, hard particles that were uncuttable.
  2.                John Dalton
    • - he developed an atomic theory based on oberservations gathered from many experiments from combining elements
    • - his theory was: all substances were made of atoms. ( atoms are small particles that cannot be created, divided, or destroyed.
    • - atoms of the same element are alike and atoms of different elements are different.
    • -atoms join with ather atoms to create new substances
  3.     J. J Thomson
    • - was the first person that atoms can be divided
    • -He experimented with a cathode blue- tube
    • - he called negetivly charged articles corpuscles ( we now call them electrons)
    • - he did the plum pudding model to show the atom with negetivly charged electrons
  4. Ernest Rutherford
    • - first to discover that atoms had a small, dense nucelus than contained posititvely charged
    •  -Gold foil experiment- aimed charged particles at a thin sheet of gold foil( trying to see where postitive charges would go)
    • - Positively charged particles passed close to the nucleus were deflected away( if it hit the nucleus in would come almost straight back.)
  5.     Rutherford's "Planetary Model"
    • Atoms
    • - is mostly empty space so electrons travel throught it
    • -has a small, dense postitivley charged nucleus
    • -electrons travel around the nucleus like planets around the sun.
  6.     Current theory- Electron Clouds Schrodinger and heisenberg.
    • - they explained that electrons do not travel in definite paths.
    • - electrons paths cannot be predicted .
    • -The current theory suggest that electrons are found in regions called electron cloud.
  7.                 Niels Bohr
    • - In 1913 Niels bohr  determined that electrons traveled around the nucleus in definite paths.
    • -He also discovered that electrons could jump from on path in one level to a path in another level
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