Atoms
Three parts of the atom:
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Protons
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Neutrons
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Electrons
Atom- the smallest component of an element having the chemical properties of the element, consisting of a nucleus containing combinations of neutrons and protons and one or more electrons bound to the nucleus by electrical attraction; the number of protons determines the identity of the element.
Dalton's Laws
1. Everything is made up of small particles.
2. A pure element is made up of the same atoms.
3. Atoms can not be created nor destroyed. (This is no longer true, we have atom smashers.)
4. In a compound, the ratio of atoms are always predictable.
5. After a chemical reaction, the atoms are rearranged inside the molecule.
In the 1800's Dalton had ideas about the atom but, he was unable to test his theory because of he did not have the proper experimental tools.
He had the first idea of what it looked like and he referred to it as the ball bearing.
His atom simply looked like a sphere with nothing inside of it or around it.
In 1880, J.J Thompson added on to Dalton's theory of the atom. He realized that the atom was not just a sphere and that it had charged particles with negitive charges inside of it. He experimented with the Cathode ray tube that glows when energy goes through it. When he experimented with this the glow inside the tube was in fact glowing and it was attracted to the magnet so there must have been matter with a charge next to it. The picture of the atom then changed, Thompson said it was a sphere with little spheres inside of it that have negative charges.
In 1909, Rutherford changed the atom again. He said that the atom had a small dense center that had smaller negative particles orbiting it. He did an experiment that used a laser beam, foil & a detector screen to show that there was space between the protons and electrons.
James Chaddwick did an experiment to show the proof of neutrons. He got a scale and put the electrons & protons on one side and the atoms on the other. When he weighed them the atom was still heavier then the protons and electrons so that must have ment there was another part to the atom. That is how he realized the neutron exsisted.
Today the atom does not look like any of these pictures. It still has a solid but dense center called the nucleus which is composed of protons and neutrons. Around the nucleus, there are electron clouds. That is an area in the atom where the electron is most likely to be found.
