number (atomic weight) = p + n Representative atoms: 2311Na, 35 17 Cl, 126C, 11H, 147N, 42He, 168O, 3919K Isotopes Isotopes - have same number of protons (or atomic number) i.e. carbon-12 vs. carbon-14 Radioisotopes – unstable isotopes used in research & medicine Proton Neutron Electron Hydrogen (1H) (1p+; 0n0; 1e–) Deuterium (2H) (1p+; 1n0; 1e–) Tritium (3H) (1p+; 2n0; 1e–) Structure of Atoms Electron filling rules – 1st shell = 2 e; 2nd shell = 8e; 3rd shell = 18e; 4th shell = 32e Valence…
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