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Jan 1, 1001
Greek's Atoms
Atomos- “cannot be divided”
People from Greece about 2,500 years ago wondered about matter.
Early Greek philosophers thought that matter was made of tiny particles. -
Dalton's Atoms
His idea was that he believed everything was made of atoms and that they were very tiny and couldn’t be divided. His idea also included that atoms had different masses and weights.
Atoms are indestructible and unchangeable. Elements are characterized by the mass of their atoms. All the atoms of an element are exactly alike. An atoms is a hard sphere that was the same throughout. -
Crooke's Atoms
William Crookes did experiments with a glass, vacuum tube. The glass tube has two pieces of metal called electrodes. One electrode, the anode, has a positive charge. The other, the cathode, has a negative charge.
These rays were called cathode rays. Crooke’s tube is known as cathode-ray tube, or CRT. -
Thomson's Atoms
Placed a magnet beside the tube from Crooke’s experiments. The beam is bent in the direction of the magnet.
Discovered electrons
Light cannot be bent by magnets
he reasoned that the particles must be negatively charged or electrons
positive electrons would be protons
a sphere of positive charge- negative electrons evenly mixed in
the makes the atom neutral
“chocolate chip cookie dough” or (plum pudding) -
Rutherford's Atoms
Rutherford experimented what would happen when they fired fast moving, positively charged bits of matter called alpha particles, at a thin film of a metal such as gold.
Alpha Particle- 2 protons and 2 electrons
Alpha particles are positively charged and are actually from unstable atoms and since they are positive they repel from particles of matter who also are positive.
Alpha particles were aimed at a thin sheet of gold foil that was only 400 nm thick. The foil was surrounded by a fluorescent s -
Bohr's Atoms
Niels Bohr- The electrons are in orbits, or energy levels around the nucleus.
1 orbit- 2 e
2 orbit- 8 e
3 orbit- 8 e
4 orbit- 8/18 e Electrons are in unpredictable motion
*in the electron cloud -
Heisenberg
He calculated the behavior of electrons. He understood the patterns of the atom's electrons. He came up with the cloud theory. The cloud theory stated that the atoms moved around and widely spreading.
