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18 Cards in this Set
- Front
- Back
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This guy first used the term atom to descrive the smallest unit of matter
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Democritus
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Law of Conservation of Mass
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Lavoisier: the total mass before a chemical change is the same as after a chemical change.
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Law of Definite Composition(/Proportion)
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Proust: In a given compound, the relative number and kinds of atoms are constant OR in a given compound, there is always present the same proportion of elements by mass
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4 points of Dalton's Atomic Theory
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1. All elements are composed of small, indivisible particles called atoms.
2. Atoms of a given element are identical. Atoms of diff. elements are diff. and have diff. properties. 3. In a chemical rxn atoms are neither created nor destroyed. 4. When 2 or more elements combine, a compound is formed. Compounds always have the same relative # and kids of atoms. |
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Which of Dalton's 4 points is/are wrong?
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1. atoms are indivisible. Nuclear fusion/fission
2. Atoms of a given element are identical. isotopes. |
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Law of Multiple Proportions
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If 2 or more compounds are composed of the same 2 elements, the ration of the masses of the 2nd element combines w/ a certain mass of the 1st element is always a ration of small whole #'s.
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He discovered the election and proposed to plum pudding atomic
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J.J. Thomson
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His work on cathode rays showed that electrons were negatively charged.
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William Crooke
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From his famous gold foil experiment, he concluded that an atom is mostly empty space with a small, dense, positively charged nucleus
(mass of a proton is 1amu/dalton) |
Rutherford
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He is credited with discovering the neutron.
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James Chadwick
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proposed that electrons orbit the nucleus similar to the way the planets revolve around the Sun (wrong)
the ____ of atom |
Niehls Bohr
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The modern atom is called
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-electron cloud
-quantum cloud-model |
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In the electron cloud , what is special about the electrons?
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We can only predict the probability of finding an electron in a certain area at a certain time.
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What non-SI unit do scientists often use to give atomic diameters?
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angstrom = 10^-10 m
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We can never at any given time give an electron's exact location and speed. We can only predict the probability of where it is at any given moment is called the...
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Heisenberg Uncertainty Principle.
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Define proton
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+ charged particles located in the nucleus. Mass is approximately 1 amu.
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Define Neutron
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neutral particle located in the nucleus. The mass of a neutron is approximately 1 amu.
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Define Electron
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- charged particle located in area around the nucleus. Mass of electrons is negligible (fairly insignificant)
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