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28 Cards in this Set
- Front
- Back
Created the plum-pudding (oatmeal & raisins) model of atoms |
JJ Thomson |
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Performed an oil drop experiment to study electrons in 1910 |
Robert Millikan |
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Discovered neutrons using alpha particle bombardment |
James Chadwick |
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First said that matter was made of smaller particles called atoms |
Democritus |
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Used a cathode ray tube in his experiment in 1897 |
JJ Thomson |
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Used scientific experimentation and summarized the work of others |
John Dalton |
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Developed the Atomic Theory in 1806 |
John Dalton |
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Discovered the nucleus as a tiny, dense structure surrounded by mostly empty space |
Ernest Rutherford |
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Discovered the first subatomic particle: the electron |
JJ Thomson |
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Found that each element has a unique atomic number using X-rays |
Henry Moseley |
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Performed experiment using gold foil and a radioactive source (1906) |
Ernest Rutherford |
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Said that electrons orbit the nucleus in circular paths and that they have different energy levels, a pioneer in quantum mechanics (1913) |
Neils Bohr |
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He rejected Democitus’ idea of atoms |
Aristotle |
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Found the exact charge of the electron and its approximate mass (1/1,840th the mass of a proton) |
Robert Millikan |
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Used emission spectra to study energy and electrons(quantum levels) |
Neils Bohr |
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Master of Measurement, Law of Conservation of mass, late 1700s |
Antoine Lavoisier |
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Father of Scientific Method, master data collector, 1st chemist, 1600s |
Robert Boyle |
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Discovered “air” was actually many “different airs”, discovered oxygen |
Joseph Priestly |
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How and why are Thomson’s and Rutherford’s models different? |
Thomson’s model suggested that the atom was like a ball of positively charge with the negatively charge electrons uniformly dispersed throughout. It was developed before the nucleus had been discovered. Rutherford’s model shows the tiny positive nucleus in the center with the electron orbiting it with most of the atom being empty space. |
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What are the three subatomic particles and what charged do they have? |
Protons- positive, neutrons-neutral, electron-negative |
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What two particles are found in the nucleus of an atom? |
Protons and neutrons |
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What is an isotope? Give two examples. |
Atoms of the same element with a different number of neutrons Examples: Carbon-12 & Carbon-14, Uranium-235 & Uranium-238 |
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What does the atomic number correspond to in an atom? |
The number of protons in the nucleus |
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Why are electrons not included in determining the mass number? |
The mass of an electron is so small it is not counted. Their mass is about about 1/2000th the mass of a proton or neutron. |
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Explain why the atomic masses of elements on the periodic table are not whole numbers. |
The atomic mass on the periodic table is the average mass of all the atoms including all of the different isotopes of the element. |
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What do the numbers 7 and 3 on the following nuclear symbol for Lithium correspond to? |
The 7 is the mass number which is the protons plus neutrons. The 3 is the atomic number which is the number of protons |
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How would you determine the number of neutrons? |
You would subtract the atomic number (3) from the mass number (7). 7 – 3 = 4 neutrons |
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In their elemental or natural state atom are neutral. How do the number of electrons and protons compare in this state? |
The number of protons and electrons are equal in neutral atoms. |