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Equivalent resonance structures contain the same number of single or multiple bonds and each atom ahs the same formal charge
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The best resonance structure has the following criteria:
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Non-equivalent resonance structures have different numbers of bonds and different formal charge distribution
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1. Smaller formal charges (+ or -) are preferred over larger ones
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Formal charge = # of valence electrons - (# bonded electrons + lone pairs)
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2. Like formal charges on adjacent atoms are not desirable
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Overall charge = sum of formal charges
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3. Negative formal charges should reside on a more electronegative atom
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Intramolecular forces occur within molecules and are strong forces
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London dispersion forces occur in all molecules and get stronger as the length of the molecule increases
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Atomic orbitals overlap to form a new orbital with a pair of opposite spin electrons. This is valence bond theory
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Sigma bonds are the first single bonds between 2 atoms
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Hybrid orbitals can be determined by the VSEPR structure of a molecule, or by looking at the total # of electron groups
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Pi bonds are the second or third bonds between 2 atoms
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Partially filled orbitals in the hybridized orbitals represent single bonds
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Unhybridized p orbitals represent Pi bonds
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Filled orbitals represent lone pairs
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To create equal orbitals, you may have to promote an ns electron to a np electron
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Partially filled s and p orbitals can overlap to share electrons
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Intramolecular forces occur within molecules and are strong forces
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London dispersion forces occur in all molecules and get stronger as the length of the molecule increases
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Intermolecular forces occur between molecules and are weaker forces
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London dispersion forces are caused when an instantaneous dipole attracts another instantaneous dipole
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The strength of an intermolecular force is dependent on the size of the molecule, the surface area of the molecule, and the polarity of the molecule
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Created by the constant movement of molecules
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Dipole-dipole forces exist in all polar molecules
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London dispersion forces are the weakest IMF
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A permanent dipole exists in polar molecules due to the difference in electronegativity of bonded atoms
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Hydrogen bonding occurs when hydrogen bonds with N, F, or O
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The positive end of one molecule will attract the negative end of another and vice versa
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Hydrogen bonds are very strong IMF
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Ion-dipole forces occur between ions and polar molcules
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Stronger IMFs lead to higher boiling points and lower melting points
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Cheatography n. The art of mapping complex subjects into clear, instantly navigable reference guides.
