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understand the Atom
Vocabulary for Understanding the Atom
| Question | Answer |
|---|---|
| atom | smallest particle of an element that still represents that element |
| electron | particle with one negative charge |
| nucleus | center of the atom where protons and neutrons are located |
| proton | particle with one positive charge |
| neutron | neutral particle found in the nucleus |
| electron cloud | part of the atom outside the nucleus that contains the electrons |
| atomic number | the number of protons in an atom of an element |
| isotope | an atom of the same element that have different numbers of neutrons |
| mass number | is the sum of the number of protons and neutrons in an atom's nucleus |
| average atomic mass | the average mass of the element's isotopes |
| radioactive | elements that spontaneously emit radiation |
| nuclear decay | a process that occurs when an unstable atomic nucleus changes into another more stable nucleus by emitting radiation |
| ion | an atom that is no longer neutral because it has gained or lost electrons |
| Democritus | said atoms are uncuttable, they are the smallest particle of matter, they are indivisible and not destructible |
| Dalton | all matter is made of atoms, atoms can not be created or destroyed, all compounds are combinations of 2 or more atoms |
| JJ Thompson | discovered the electron |
| Ernest Rutherford | showed most of the mass of the atom is in the nucleus and the rest is empty space |
| Niels Bohr | said electrons travel in energy levels around the nucleus |
| Chadwick | added the addition of neutrons to the nucleus of the atom |
| quark | smaller parts of the protons and neutrons |