The Electron Cloud Model-Our
modern model of the atom suggests that
there are clouds of electrons surrounding
the nucleus and that the exact location of
the electron cannot be predicted.
Niels Bohr (1913)-- suggested
that electrons travel around the
nucleus in definite paths.
Ernest Rutherford (1909-1911) Discovers that the
atom is mostly empty space with a small dense and
positively charged center called the nucleus.
J.J. Thomson (1897)- discovered the electron which shows that the atom is, in
fact, divisible. There are smaller particles within the atom itself. An atom has
NO overall charge if it contains the same number of protons and electrons
John Dalton ( late 1700s)-- English School teacher-Developed the 3-part atomic theory based on his
observations and published it in 1803
His theory states: 1) All substances are made of matter. 2) Atoms of the same element are exactly alike*,
atoms of different elements are different. 3) Atoms join with other atoms to make new substances--
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Democritus (440 BC)--Greek Philosopher-Came up with the idea of the atom
He named this particle atom, which comes from the Greek word atomos for "indivisible"