* A negative charge: Hydroxyl ions have a single negative charge (OH⁻). This is because they are formed when a water molecule loses a proton (H⁺).

* An oxygen atom bonded to a hydrogen atom: The hydroxyl ion consists of an oxygen atom (O) covalently bonded to a hydrogen atom (H).

* The ability to accept a proton: Hydroxyl ions are basic because they can accept a proton (H⁺) to form water (H₂O). This is the key characteristic of a base – it can neutralize an acid by accepting its proton.

In summary, a hydroxyl ion (OH⁻) is a negatively charged molecule with an oxygen atom bonded to a hydrogen atom. It is responsible for the basic properties of a solution.