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💏intro to chemistry review

Electron Pair Donor

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

An electron pair donor is a species, typically a Lewis base, that provides a pair of electrons to form a covalent bond with another species, typically a Lewis acid. This donation of an electron pair is a key concept in understanding the behavior of Lewis acids and bases.

5 Must Know Facts For Your Next Test

  1. The electron pair donated by a Lewis base is typically a lone pair of electrons on an atom with a high electronegativity, such as oxygen, nitrogen, or a halogen.
  2. The formation of a coordinate covalent bond between a Lewis acid and a Lewis base is a key step in many chemical reactions, including acid-base reactions and the formation of complex ions.
  3. The strength of the Lewis acid-base interaction is determined by the relative electronegativity of the species involved, with stronger interactions occurring between species with a larger electronegativity difference.
  4. Electron pair donors can be neutral molecules, such as water or ammonia, or negatively charged ions, such as hydroxide or chloride.
  5. The ability of a species to act as an electron pair donor is an important factor in determining its reactivity and behavior in chemical systems.

Review Questions

  • Explain the role of an electron pair donor in the formation of a coordinate covalent bond.
    • An electron pair donor, typically a Lewis base, provides a pair of electrons to a Lewis acid, forming a coordinate covalent bond. This donation of an electron pair allows the Lewis acid to achieve a more stable electron configuration, while the Lewis base gains stability by sharing its electron pair. The formation of this coordinate covalent bond is a key step in many chemical reactions, as it allows for the interaction and combination of different species to produce new compounds.
  • Describe the relationship between the electronegativity of an electron pair donor and the strength of the Lewis acid-base interaction.
    • The strength of the Lewis acid-base interaction between an electron pair donor and a Lewis acid is directly related to the relative electronegativity of the species involved. Electron pair donors with higher electronegativity, such as oxygen, nitrogen, or halogens, are able to form stronger interactions with Lewis acids, as the difference in electronegativity between the donor and the acceptor is larger. This greater electronegativity difference results in a more polarized and stable coordinate covalent bond, which is a key factor in determining the overall reactivity and behavior of the chemical system.
  • Analyze the role of electron pair donors in the context of acid-base reactions and the formation of complex ions.
    • Electron pair donors play a crucial role in acid-base reactions and the formation of complex ions. In acid-base reactions, the electron pair donor (the Lewis base) provides a pair of electrons to the acid (the Lewis acid), forming a coordinate covalent bond and producing a new, more stable species. Similarly, in the formation of complex ions, the electron pair donor (often a negatively charged ion or a neutral molecule with a lone pair) donates its electrons to the central metal ion (the Lewis acid), creating a stable complex with unique properties. The ability of electron pair donors to participate in these reactions is a fundamental aspect of Lewis acid-base theory and is essential for understanding the behavior of chemical systems.