Q.Define electrophiles and nucleophiles. Find out the electrophiles and nucleophiles among the following: CN-, BF3, ROH, RO-, +CH3, H+, H2O

BF3 is not a nucleophile (it is an electrophile).

Nucleophiles are electron-rich species that donate a lone pair, e.g. CN-, CH3O- and NH3 (lone pair on N). BF3 has boron with an incomplete octet (only 6 electrons), so it accepts …

BCl3 is the electrophile because boron has an incomplete octet and is electron-deficient.

An electrophile ("electron-loving") is a species that is electron-deficient and accepts an electron pair.

• BCl3: boron has only 3 bond pairs (6 electrons) around it — an incomplete octet — so it readily accepts an electron pair; it is a classic electrophile/Lewis acid. …

Nucleophiles are electron-pair donors; OH⁻ and H₂O both have available lone pairs and are classic nucleophiles, while the other options mix in electrophiles.

A nucleophile ('nucleus-loving') is a species rich in electron density — usually bearing a lone pair and/or a negative charge — that attacks an electron-deficient (electrophilic) centre, forming a new bond by donating its electron pair.

• (a) OH⁻, H₂O: OH⁻ carries a negative charge and lone pairs; H₂O is neutral but has two lone pairs on oxygen. Both readily donate electrons — both are nucleophiles. ✓ …

Electrophiles are electron-poor species (often positively charged or with an incomplete octet) that attack electron-rich centres; CH3+ is the only such species among the options.

An electrophile ("electron-loving") is a reagent that is deficient in electrons and hence seeks out a pair of electrons from another species during a reaction. Electrophiles are typically positively charged, or neutral species with an incomplete octet/empty orbital.

A nucleophile ("nucleus-loving"), in contrast, is electron-rich — usually bearing a lone pair or a negative charge — and donates electrons to an electrophilic centre.

Checking the options:

• C2H5O- (ethoxide ion): negatively charged, has lone pairs to donate → nucleophile. …