Download History of Atomic Theory • Democritus: Atom meaning “unable to

yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

History of molecular theory wikipedia, lookup

Unbinilium wikipedia, lookup

Ununennium wikipedia, lookup

Extended periodic table wikipedia, lookup

Tennessine wikipedia, lookup

Periodic table wikipedia, lookup

Dubnium wikipedia, lookup

History of Atomic Theory
 Democritus: Atom meaning “unable to divide”. (440 BCE)
 Dalton’s Atomic Theory: (1803)
o All substances are made of atoms.
o Atoms cannot be created, divided, or destroyed.
o Atoms of the same element are exactly alike. Atoms of
different elements are different.
o Atoms join together with other atoms to make new
 JJ Thomson: “Plum pudding” Model (1897)
o Discovered the electron.
 Rutherford: “Gold foil” experiment (1911)
o Atom has a positive center (nucleus).
o Atoms are made up of mostly empty space.
 Niels Bohr: Electrons are found in energy levels (1913).
o Compared electrons, orbiting the nucleus in energy levels, to
planets orbiting around the sun.
 Modern Model: Electrons are believed to behave more like waves
on a vibrating string than like particles.
o The best scientists can do is calculate the chance of finding
an electron in a certain place within an atom.