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21 Cards in this Set
- Front
- Back
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Who came up with the first theory of atoms?
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In the 4th century BC, Democritus suggested that the universe was made of indivisible units
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What did Dalton add to the atomic theory?
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All atoms of a given elements were exactly alike, and atoms of different elements could join to form compounds
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How did Thomson discover the electron?
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his cathode ray tube experiment suggested that cathode rays were made of negatively charged particles that come from inside atoms
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What doe Rutherford`s atomic model propose?
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he proposed that most of the atom was concentrated at the atom`s center
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What is the difference between protons, neutrons, and electrons?
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mass, charge, and location of the atom
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What do atoms of an element have in common with other atoms of the same element? Different?
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same # of protons
different # of neutrons |
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Why do isotopes of the same element have different atomic masses?
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# of neutrons differ
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What unit is used to express atomic mass?
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unified atomic mass units
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What is the modern model of the atom?
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In the model, electrons can be found only in certain energy levels, not between levels. Furthermore, the location of electrons cant be predicted precisely
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What do the energy levels that are filled depend on?
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# of electrons
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What makes an electron jump to a new energy level?
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gaining or losing energy
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Unreacted atoms have no overall ___ because protons and electrons ____
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charge
cancel |
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____ holds the atom together
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electric force
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calculating neutrons
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mass - protons = neutrons
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____ abundunce determines the average atomic mass
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isotope
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amt (mol) --> mass (g)
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x by molar mass
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mass (g) --> amt (mol)
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divide by molar mass
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Electron location is limited to ____
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energy levels
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Electrons act like ____ on a _____
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waves on a vibrating string
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four types of orbitals
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s, p, d, f
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atoms absorb or emit light at certain wavelengths
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high energy photons- short wavelengths
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