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23 Cards in this Set
- Front
- Back
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Law of conservation of matter
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When a chemical reaction takes place, matter is neither created nor destroyed.
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Law of constant composition
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Multiple samples of any pure chemical compound always contain the same percent of each element.
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John Dalton
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Atomic Theory (5)
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Thomson
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Discovered electron in 1897.
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Thomson and Goldstein
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Discovered proton in 1907.
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Chadwick
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Discovered neutron in 1932.
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Plum Pudding
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Thomson; Negative electrons in positive pudding. Protons yet to be discovered.
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Rutherford
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Alpha Particle with Gold Foil in 1909.
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Why did only some of the particles reflect at wide angles?
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Because sometimes the beam passes through the empty space, which debunks Thomson.
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Why did some of the particles reflect at wide angles?
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Because there is a small positively charged thing, which Rutherford named nucleus.
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Nucleus
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Holds an atom's protons and neutrons.
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How are electrons held in the atom?
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The attraction between + and - charges holds the electrons in the atom.
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Atomic Number
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Number of protons; alone determines identity of atom.
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Mass Number
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Protons + number of neutrons.
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Isotopes
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Different versions of same element; same atomic number, but different number of neutrons. Different masses.
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Atomic Mass
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Each isotope's atomic mass is multiplied by its percent abundance and results summed.
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Law of Mendeleev
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Properties of elements recur in regular cycles when arranged in increasing atomic mass.
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Atomic Size
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Atomic radius increases down a group; increases right to left.
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Ion
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Atom without balanced electron-proton; with net charge.
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Anion
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- Ion.
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Cation
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+ Ion
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First ionization energy
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Minimum amount of energy required to remove 1 electron from an atom.
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Ionization Energy
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Decreases down a group; decreases right to left.
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