Atomic Theory is the study of atoms. Atoms are the smallest forms of matter that can still be considered/recognized as elements. Atoms are what make up everything on our earth, from molecules to monkeys. Atoms are joined together to make molecules, which are in turn joined together to make everything else. To give you an idea of the size of an atom, Encarta Online describes it as being “so small that a single drop of water could contain more than a million million billion atoms”. I think they could’ve used more scientific terms, but you get the idea at least.
In the early half of the 19th century, John Dalton (a chemist, who many consider the person who started the atomic theory) proved that atoms are always joined together basically the same way, and that the smallest part of a chemical compound was a molecule. He said that “All atoms of an element have the same chemical behavior, but different elements have atoms with different chemical properties.”
Scientists weigh gases by holding the same amount of a gas in a container and then wighing it. In the 20th century, most scientists used oxygen as the standard gas to compare other gases’ weights. It is relativly easy to measure the weights of liquids and sloids, the same procedure for gas is followed, more or less. In the early 1960s, though, the international union of chemistry and physics agreed that there would be a new standard, carbon isotope (carbon-12).
British physicist Ernest Rutherford found and proved that an atom’s mass is concentrated in its its nucleus, which is the center of the atom. He also gave the idea that parts of an atom, called its electrons, orbit the nucleus. He said that the electrons were “negatively charged” and that the protons were “positively charged”. He said that the two charged always equalled each other/cancelled each other out (making it neutral).
Danish physicist made what became known as the “Bohr Theory” for atoms and atomics theory. He stated that electrons were arranged in seven different orbits, or “quantum levels”. He said that each of these levels was capable of holding a different, limited number of electrons.
In 1919, Ernest Rutherford tried to bombard nitrogen gas with alpha particles, and when he tried this, some of the alpha particles collided with the nitrogen nucleuses.They then emitted a postively-charged proton. More research helped find that protons are part of the nucleus, along with neutrons.
There are two nuclear processes, called fission and fusion, provide huge amounts of energy to us by two different processes. Fission splits an atom, while fusion invlves fusing two nucleuses. Scientists figured out how to do nuclear fission in 1930, when the discovered that by splitting the nucleuses of Uranium, they could produce large amounts of energy.
Atomic theory has moved along quite a bit since discovered. I can only wonder what we will find out within the next 25 years! A long time ago, my grandpa didn’t have electricity when he was growing up. I can’t imagine how he survived without electicity. Many years from now, my grandchildren will probably wondering, “How did grandpa ever survive without Cold Fusion?”