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unit 2-section 1
vocab words
| Question | Answer |
|---|---|
| Atom | the smallest particle of an element that can exist alone or in combination |
| Neutron | a particle that has a mass nearly equal to that of the proton but no electrical charge is present in all atomic nuclei except those of hydrogen |
| Proton | a very small particle that occurs in the nucleus of every atom and has a positive charge of electricity |
| Electron | a very small particle that has a negative charge of electricity and travels around the nucleus of an atom |
| Ion | an atom or group of atoms that carries an electric charge |
| Isotope | any of two or more species of atoms of a chemical element with the same atomic number and position in the periodic table and nearly identical chemical behavior but with differing atomic mass or mass number and different physical properties |
| Atomic number | an experiemntally determined number characteristic of a chemical element that represents the number of electrons outside the nucleus and that determines the place of the element in the periodic table |
| Nucleons | protons or neutrons in the atomic nucleus |
| Nuclide | a species of atom charcterized by the constitution of its nucleus and hence by teh number of protons, the number of neutrons, and the energy content |
| Mass number | an integer that expresses the mass of an isotope and designates the number of nucleons in the nucleus |
| John Dalton | developed the Atomic theory |
| JJ Thompson | discovered the electron using the Cathode Ray Tube |
| Democritus | viewed matter as made of smaller particles |
| Ernest Rutherford | discovered the existence of nucleus using the Gold Foil Experiment |
| Neils Bohr | developed the planetary model |
| James Chadwick | discovered the neutron |
| Robert Millikan | discovered the electron charge and mass of an electron using the Oil Drop Experiment |