English: The ethane molecule spends 99% of its time in a specific conformation. The so-called staggered conformation is reached if, when the molecule is seen from a position on the C-C axis (as in the second half of the animation), the H atoms of the front C atom are exactly between the H atoms of the other C atom. This conformation is energetically favoured for quantum mechanical reasons (see hyperconjugation), rather than the old textbook notion of steric hindrance. Thus, the molecule spends most of the time in that conformation, regardless of pushes from other molecules around it. Ref.: Hyperconjugation not steric repulsion leads to the staggered structure of ethane Pophristic, V. & Goodman, L. Nature 411, 565–568 (2001) Abstract