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Counting particles - o ions atom(or molecule with missing...

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Counting particles counting nucleons o atomic number number of protons in the nucleus Z is unique for each element o mass number (M) number of protons and neutrons in the nucleus o symbols for nuclei: nuclide symbols are 'top heavy': mass number is always the left superscript, and is always bigger than or equal to Z, the left subscript sometimes Z is omitted names are sometimes written out: element name dash mass number , e. g. uranium-235 nuclide names use mass not atomic number (carbon-12 is correct; carbon-6 is not) counting electrons o atoms number of electrons equals number of protons chief role of nucleus in chemistry: nucleus determines number of electrons
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Unformatted text preview: o ions atom (or molecule) with missing or extra electrons charge = #protons - #electrons charge given as a trailing superscript in nuclide symbols positive ions are cations; negative ions are anions nuclear tug-of-war • electrostatic repulsion pushes protons in nuclei apart • strong nuclear force holds nucleons in nuclei together • energy required to break up a nucleus is millions of times the energy required to break up a chemical bond o that makes nuclei inert in chemical reactions. • range of strong nuclear force is about 10-14 m; stable nuclei are small . o large nuclei tend to be unstable (radioactive)...
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