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vocab chps 12 & 13
Stack #59956
word | definition |
---|---|
element | a pure substance that cannot be seperated or broken down into simpler substances by physical or chemical means |
compound | a pure substance composed of two or more elements that are chemically combined |
mixture | a combination of two or more substances that are not chemically combined |
atom | the smallest particle into which an element can be divided and still retain all of the properties of that element |
proton | the positivley charged particles of the nucleus |
electron | the negativley charged particles found in all atoms |
neutron | the particles of the neucleus that have no charge |
periodic | having a regular, repeating pattern |
periodic law | a law that states that the chemical and physical properties of elements are periodic functions of their atomic numbers |
atomic number | the number of protons in the neucleus of an atom |
atomic mass | the weighted average of the masses of particles in atoms |
isotope | atoms that have the same number of protons but have different number of neutrons |
valence electron | the electrons in the outermost energy level of an atom |
John Dalton | atomic theory |
Ernest Rutherford | positve charge nucleus, atom mostly empty space electrons travel around the nucleus |
Niels Bohr | electrons travel in clouds |
Democritus | 1st to come up with the idea of an atom |
Dmitri Mendeleev | father of the periodic table, aranged elements by atomic mass |
Henry Moseley | rearranged periodic table by atomic number |
J. J. Thomas | small particles in atom |