CHEM-UA 225 Lecture Notes - Lecture 5: Covalent Bond, Valence Electron, Bond Energy
24 Mar 2020
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Document Summary
Form bonds by sharing electron pairs rather than completely transferring electrons: not strongly electronegative, not strongly electropositive, similar electronegativities. Involves mutual sharing of 1+ electron pairs between atoms: 2+ atoms joined by covalent bonds constitute a molecule. When 2 atoms are identical/have equal electronegativities, electron pairs are shared equally: heat is liberated, same amount of heat (energy) has to be supplied to hydrogen molecule to break it apart into atoms. Breaking apart 1 mole (2 g) of hydrogen molecules into atoms requires 104 kcal (or 435 kj*) of heat: bond energy (be): different for bonds between different atoms, h h bond: Very strong bond: shared electron pair is attracted to both hydrogen nuclei. Hydrogen atom: valence electron is associated w/ only 1 nucleus: other forces in hydrogen molecule tend to counterbalance attraction between electron pair & nuclei, forces are repulsion between 2 like-charged nuclei & repulsion between.
