Determine the functional groups in the unknown - chemical reactivity such as ozonolysis tells us that there is an alkene in the unknown, IR spectral data can be very useful. Propose a structure for the unknown and measure each clue or hint from 1 against your proposal. Refine the structure if necessary based on 6, keeping parts that are consistent with 1. Determine any stereochemical features in your proposed structure and determine if they are consistent with 1. Lewis structures follow the octet rule, show all lone pairs and charges.
Resonance occurs in systems.
Be able to estimate the importance of resonance structures. In Fischer projections - the cross bonds are forward out of the plane. In line drawings a heavy bond is forward out of the plane and a dashed bond into the plane. In Newman projections the back carbon is hidden by the front carbon.