Unformatted text preview: The two ions are held together in an ionic bond because the
oppositely charged ions attract each other as described by Coulomb's Law.
Ionic compounds, when in the solid state, can be described as ionic lattices whose shapes are
dictated by the need to place oppositely charged ions close to each other and similarly charged
ions as far apart as possible. Though there is some structural diversity in ionic compounds,
covalent compounds present us with a world of structural possibilities. From simple linear
molecules like H2 to complex chains of atoms like butane (CH3CH2CH2CH3), covalent
molecules can take on many shapes. To help decide which shape a polyatomic molecule might
prefer we will use Valence Shell Electron Pair Repulsion theory (VSEPR). VSEPR states that
electrons like to stay as far away from one another as possible to provide the lowest energy (i.e.
most stable) structure for any bonding arrangement. In this way, VSEPR is a powerful tool for
predicting the geometries of covalent molecules.
The development of quantum mechanics in the 1920's and 1930's has revolutionized our
understanding of the chemical bond....
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