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Transcript of Timeline
Models of the Atom
Joseph John Thomson's Model of the Atom
The modern model of the atom was invented by the combined efforts of Louis De Broglie, Werner Heisenberg, Albert Einstein and Erwin Schrodinger. The Quantum Mechanical atomic theory is a mathematical model that is designed to find the probability of locating an electron within a certain space of the nucleus. The Quantum Mechanical model is the most accurate model we have to this date. This model still incorporates Bohr's model with the understanding of atomic energy levels.
John Dalton's model
of the atom
Earnest Thompson Rutherford's
Model of the Atom
Neils Bohr's Model
of the Atom
Louis De Broglie, Werner Heisenberg,
Albert Einstein and Erwin Schrodinger
Model of the Atom
John Dalton's model of the atom was created in 1803. Dalton stated that matter is composed of very small things calls atoms. Dalton made the original laws of the atom known today as the particle theory. Dalton's model is very basic and did not include a nucleus and electrons. Dalton's theory perfected the ancient greeks theory and although had errors led the way for more exploration. Dalton"s model of the atom is called the billiard ball because it is very basic and so is a billiard ball.
Joseph John Thomson's Atomic Theory proposed the idea that atoms were actually made up of even smaller particles. He believed that atoms are made of negative electrons (charge of negative electricity) that float in a positive charge. Thomson's model did not have a nucleus and the electrons were not arranged. This theory still had many errors but the idea of electron's was a huge step in the right direction. Thomson actually discovered the electron in 1897 but proposed the atomic theory on 1904. Thomson's model of the atom is called the plum pudding or raisin bread model because the electrons float in a "soup" of positive charge, just like plum's float in pudding or the raisins in raisin bread are randomly placed like the electrons in the atom.
Rutherford's atomic theory was the first model of an atom that had a nucleus which is a dense, tiny, positively charged core. Around the nucleus lighter negatively charged electrons orbit the nucleus like a solar system in circles. The model has been refereed to as the planetary model because when the electrons orbit the nucleus it resembles the planets orbiting the sun.
Bohr's model of the atom was perfecting Rutherford's model of the atom. His atomic theory stated that the electrons don't orbit the nucleus in perfect circle's. They orbit in a fixed (quantized) curved path.There are different energy levels and an electron can jump from their orbit path to another orbit by absorbing or emitting a proton. Bohr also discovered radiation which is how he came up with his theory and the paths of the electrons orbiting the nucleus. Bohr knows that the electrons can't orbit around the nucleus in a spiral because the electrons would lose energy because it is orbiting in a curved path which causes it to accelerate and would lose energy and hit the nucleus and atoms would no longer exist.
Discovery of Radiation (Electrons Paths)
Is Science Ever Finished
Is science ever finished? NO! Science just keep going and going. Science is all about how things work and why things do what they do. Take this for example: we have not been successful yet in finding a sustainable cure for all types of cancer. This means that science is not over this scientific issue doe snot have a cure. If we ever find a cure for cancer science must be done right? We have solved the problem and their is nothing more to find out about cancer. Right? WRONG! We can always improve out cancer cure we can improve the accuracy of where the cancer is. We can reduce the wait time for the results meaning the machines work quicker. We are never done we can always improve. Just like with the atoms we can always keep improving the atoms and how close we are to what the actual atom is (what is looks like and contains). Maybe one day we will find out that their is another particle in the atom or that electrons don't actually exist. Science is never over, Science is so big and broad and covers tons of things and we can always improve on what we know. Science is and NEVER will be over.
J.J. Thomson's Model
J.J. Thomson discovered that atoms have electrons which are a negatively charged particles. He did this with a Cathode Ray Tube experiment. He put two pieces of metal (the first without a hole and the second with a hole in the middle)in a completely sealed glass cathode ray tube (pop bottle shape). He connected the two pieces of metal to a power source on the outside of the cathode ray tube. When he connected the power source a ray shot from the first piece of metal through the whole in the second piece of metal and to the end of the cathode ray tube. When it hit the end of the cathode ray tube it created a glowing spot because if the special coating that was on the inside of the cathode ray tube. This happened because in the negatively charged electrons in the first piece of metal were attracted to the second piece of metal with an opposite charge. The electrons were moving so fast that they went past the second piece of metal and hit and end of the cathode ray tube. Also he put magnets around the cathode ray tube and since the electrons are negatively charge they are attracted to the positive magnet (opposite) proving that their is a smaller particle inside atoms which has a negative charge. This is an electron..
Rutherford's Gold Foil Experiment
Rutherford did this experiment to prove that atoms are mostly empty space and a small volume of the atom was most of the mass of the atom. He used radioactive particles and fired them at thin gold foil, around the thin gold foil he put a sheet coated in ZnS which would project a light when hit with a radioactive (alpha) particle. An alpha particle is is tiny and positively charged and much smaller then an atom. He shoot the alpha particles at the thin gold foil and most of the alpha particles hit the ZnS sheet that was after the thin sheet of gold foil. About 1/8000 hit the ZnS sheet that was before the thin gold foil sheet. This means that most of the alpha particles were going through the thin sheet of gold foil. This proved that the gold foil was mostly empty space and gave lots of room for the alpha particles to pass through, and hit the ZnS sheet on the other side emitting light. About 1/8000 alpha particles were bounced back and hit the ZnS sheet emitting light before the thin sheet of gold foil. This means that the alpha particle hit the sheet of gold foil where their is actual matter and bounced back. The gold foil experiment proved that matter is mostly empty space and that radioactive (alpha) particles can pass through because the nucleus holds most of the the mass in a small volume and the rest of the atom is mostly empty space.
The original atom
Discovered electrons (negatively charged particles)
had them floating randomly (with no structure)
Included a nucleus
Started the arrange of electrons
The electrons orbited the nucleus
Changed the orbit of the electrons and their paths.
Arranged the electrons orbit so they would not run into the nucleus and destroy the atom
Quantum Mechanical Model
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How Does Science Generate New Ideas
Science generates new ideas by never being over. Science is never over and that means new things may come to realization. People realize things they had never thought about before, by experiments, theory, testing and many other ways maybe one that we haven't even thought of yet. People make discoveries like J.J. Thomson did with his Cathode Ray experiment and like Rutherford with his gold foil experiment. Science is all about ideas. Science is taking what we know and adding to it and perfecting to it the most we can.
Taking everything we know and perfecting it
Designed to figure out the the likely hood of locating an electron within a certain area of the nucleus
I Have an Idea!
October 1, 2013