Structures of functional groups

In alcohols, the oxygen of the -OH group is attached to sp³ hybridised carbon by a sigma bond formed by the overlap of sp³ hybrid orbital of carbon with an sp³ hybrid orbital of oxygen. The figure shown below illustrates the bonding in methanol.
The C-O-H bond angle in alcohol is slightly less than the tetrahedral angle (109⁰28). It is due to the repulsion between the unshared electron pairs of oxygen.

In phenols, the –OH group is attached to sp² hybrid carbon of an aromatic ring. The C-O-H bond angle in phenol is 109⁰. The carbon-oxygen bond length (136pm) in phenol is slightly less than that in methanol (142pm). This is due to partial double bond character on account of the conjugation of unshared electron pair of oxygen with the aromatic ring.

In ethers, the four electron pairs, ie; the two bond pairs and two lone pairs of electrons around oxygen are arranged approximately in a tetrahedral arrangement. The c-o-c bond angle (111.7⁰ in methoxy methane) is slightly greater than the tetrahedral angle (109⁰28) due to the repulsive C-O bond length (141 pm) in ethers is almost the same as in alcohols (142 pm in methanol).