why do alkanes have very different melting points?

Question

why do they have different melting points. Would you think t has anything to do with inner molecular forces?

Answer 1

The longer the chains the high the melthing point because they are heavier with more molecular forces of attraction

Answer 2

I think you are refering to the "jagged," "up-and-down" melting points of alkanes as one proceeds through the series. It is that odd- and even-numbered alkane chains have different "packing" modes in the crystals. So there is no smooth progression from lower to higher melting points as one increases the number of carbon atoms.