One difference in crystal structure that even-numbered alkanes (from hexane onwards) tend to form denser-packed crystals compared to their odd-numbered neighbors. This causes them to have a greater enthalpy of fusion (amount of energy required to melt them), raising their melting point. A second difference in crystal structure is that even-numbered alkanes (from octane onwards) tend to form more rotationally-ordered crystals compared to their odd-numbered neighbors. This causes them to have a greater entropy of fusion (increase in disorder from the solid to the liquid state), lowering their melting point.
one difference in crystal structure that even-numbered alkanes (from hexane onwards) tend to form denser-packed crystals compared to their odd-numbered neighbors this causes them to have a greater enthalpy of fusion (amount of energy required to melt them) raising their melting point a second difference in crystal structure is that even-numbered alkanes (from octane onwards) tend to form more rotationally-ordered crystals compared to their odd-numbered neighbors this causes them to have a greater entropy of fusion (increase in disorder from the solid to the liquid state) lowering their melting point