Alkane angles

[Chem_Mod]

What if a molecule included an angle being larger than the ideal bond angle for a tetrahedral molecule? For example, if the bond angle was 120º instead of 109.5º, does that create angle strain? In lecture you stated that bigger ring structures than cyclohexane are less stable. Does this have to do with angle strain?

[Chem_Mod]

You are correct in that angle strain is related to angles being both smaller and larger than the ideal (109.5º for ). Also, the larger the C-C-C bond angle, the smaller the angle for the substituents on that central carbon, which would add strain. As we change those substituents, of course there would be added steric effects, but ultimately there would be increased strain due to the larger than ideal bond angle.