A Level Chemistry OCR Practice Exam

An electrophile is defined as an atom or molecule that is attracted to electrons; thus, it typically seeks to accept an electron pair from a nucleophile, which is a species that donates electrons. Electrophiles are characterized by having a positive charge or a partial positive charge that makes them electron-deficient. This attraction to electrons allows electrophiles to participate in various chemical reactions, particularly in electrophilic addition or substitution reactions.

In contrast, the other options describe different chemical entities or processes. The donation of a pair of electrons is characteristic of nucleophiles rather than electrophiles. An electron-rich center refers to nucleophilic sites in a molecule, while atoms that form ionic bonds do not exclusively define electrophiles, as ionic bonding involves a different mechanism of electron attraction and transfer.