What best describes a Lewis base?

A Lewis base is defined as a species that donates an electron pair to form a covalent bond. This concept is part of the Lewis theory of acids and bases, which extends beyond the traditional Brønsted-Lowry definition that focuses solely on protons. In this context, a Lewis base provides electrons that can be shared with a Lewis acid, which is an electron pair acceptor.

This broader definition is significant in many chemical reactions where electron movement is crucial, such as in coordination complexes and organic reactions. Understanding this concept allows for a better grasp of chemical interactions and reactivity in various contexts, making it essential for students of integrated science.

In contrast, definitions that involve proton transfer, like proton donor or acceptor, are more aligned with the Brønsted-Lowry theory and do not encompass the full scope of Lewis acid-base chemistry. Therefore, recognizing a Lewis base specifically as an electron pair donor is key to differentiating it from other types of bases.