What is the definition of a radical in chemistry?

A radical in chemistry is defined as a group of bonded elements that acts as a single atom or ion. This means that the group retains its identity and properties during chemical reactions, similar to how a single atom or ion would behave. For instance, in many chemical reactions, complex ions or functional groups, such as sulfate (SO₄²⁻) or hydroxyl (OH⁻), are treated as discrete units that can participate in various reactions.

This definition emphasizes the importance of recognizing that certain clusters of atoms can work together, functioning in a way that is distinct from their individual components. Understanding radicals is crucial when studying chemical compounds and reactions, as they help in predicting how different substances will interact based on their combined properties.

The other options present concepts that don't fully capture the idea of a radical. A single atom in a compound does not encompass the interaction or behavior of groups, while a type of covalent bond pertains specifically to the nature of connections between atoms rather than their collective behavior. Finally, an individual element refers exclusively to a single type of atom, lacking the complexity and interactions represented by a group of bonded elements.