Why wouldn't C18H18 turn out as a straight line if you were to build a model?

C18H18 is the molecular formula for a symmetrical alkane known as n-octadecane. When building a model of n-octadecane, it may appear as a straight chain due to the fact that the carbon atoms bond in a linear fashion. However, due to the nature of molecular geometry and atoms in 3D space, the model may twist or bend slightly, deviating from a perfectly straight line.