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8Sci CH4
8th Science CH4 Structure of the Atom
| Term | Definition |
|---|---|
| alpha particle | positively charged particle--consisting of two protons and two neurons--which is given off by a radioactive substance;more mass than beta particle |
| beta particle | high-speed electron given off by a radioactive substance;less mass than alpha particle and can penetrate paper but stopped by 1.5mm sheet of aluminum |
| electron | negatively charged particle with a very small mass that orbits an atom’s nucleus in an electron cloud |
| gamma ray | electromagnetic waves given off by a radioactive substance |
| neutron | uncharged particle in the nucleus of an atom; a neutron has a mass about equal to that of a proton |
| nucleus | positively charged, dense center of an atom made up of protons and neutrons around which a cloud of electron moves |
| proton | positively charged particle in the nucleus of an atom; a proton’s mass is about equal to that of a neutron |
| radioactivity | decay, or breaking apart, of unstable elements such as uranium and thorium, resulting in the release of high-energy particles |