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Dalton's Theory
- Also known as the cannonball model it decribes:
- -All atoms are composed of individual atoms. (True)
- -All atoms of a given elemnt are identical. (True)
- -Atoms of different elemnts are different. (True)
- -Compounds are formed by the combination of different elements. (True)
- -Atoms are solid element with no sub-atomic particles. (False)
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J.J. Thompon's Discovery
- J.J. Thompson found out that:
- -An atom contained negatively charged particles which are now known as electrons.
- - He nick-named the design of the atom the "plum pudding model".
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Ernest Rutherford's Experiment
- Ernest Rutherford, a student of Thompson's, discovered:
- -An atom, instead of having equal concentrations of protons and electrons had one central core with a positive charge.
- - If the existance of the nucleus is true, then most of the atom is empty space.
- -He figured this out in the gold foil experiment.
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Neils Bohr
- Neils Bohr figured out this from his studies:
- -There was indeed a central nucleus with electrons orbiting around it.
- -The space around the nucleus was made up of energy levels, each containing a specific number of electrons.
- - This model was nicknamed the planetary of solar system model.
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Schrodinger and deBroglie
- Schrodinger and deBroglie came up up with the wave mechanical model stating:
- -electrons are particles that move like a wave around the nucleus.
- -electrons move in distinct energy levels called orbitals.
- -orbital: a region of probablilty (heisenberg) or a place an electron is likely to be found.
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James Chadwick
- In 1932 Chadwick discovered:
- -by bombarding hydrogen with beryllium found that neutral gama rays were emmited.
- -he named these particles neutrons.
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Why did it take so long to discover neutrons?
- -nuetrons have no chrage
- -they have the same mass as a proton
- -they reside in the nucleus with the proton
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The Gold Foil Experiment
- In the gold foil experiment Ernest Rutherford:
- -positively charged particles were shot at a thin peice of gold foil using a Cathode Ray tube.
- -if the plum pudding model was correct the particles would have passed through because they would hit a negative elctron and go through it.
- -many of the particles were deflected and Rutherford tracked back and realized they all were deflected off something in the middle of the atom.
- -this meant there was a dense structure with a positive charge in the middle of the atom
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Neutrons
- -no charge
- -1 amu
- -found in the nucleus
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Electron
- -negative charge of one.
- -found in orbitals around the nucleus.
- -1/1836th of an amu.
- -mass is neglible.
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Proton
- -positive charge of 1
- -1 amu
- -found in the nucleus
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Amu
Unit of mass equal to one proton/neutron or 1.67x10-24grams.
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Atomic Number
number of protons (identifies elemnt)
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Mass number
- -number of protons plus number of neutrons (amu).
- -you can get it by rounding the atomic mass to the neares integer.
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Neutral Atoms
number of protons equals number of electrons
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Finding the number of subatomic particles.
- Protons- equal to atomic number.
- Electrons- equal to the amount of protons in a neutral atom.
- Neutrons- The mass number-The atomic number
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- 16- atomic number
- 16.00- atomic mass
- O- symbol
- Oxygen- name
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