Physical world and mathematics

Electronic navigational chart

An electronic navigational chart (ENC) is a standardized vector chart database issued by a government-authorized hydrographic office for use with ECDIS, conforming to International Hydrographic Organization standards.

Electronic nematicity

Electronic nematicity is a phase of matter in which electrons in a crystal spontaneously break its rotational symmetry, a concept central to iron-based and copper oxide superconductors.

Electronic nematicity in iron-based superconductors

Electronic nematicity in iron-based superconductors is the spontaneous breaking of the crystal's rotational symmetry by electronic order; in FeSe it occurs near 90 K without magnetism.

Oct 21, 2026

Electronic Nose

An electronic nose (e-nose) is an instrument that mimics biological olfaction, using an array of broadly tuned gas sensors and pattern-recognition algorithms to identify complex odors, first built in 1982.

Electronic properties of condensed matter

The electronic properties of condensed matter determine whether solids conduct as metals, semiconductors, or insulators, with band gaps and electron interactions explaining behavior from silicon to superconductors.

Electronic speckle pattern interferometry

Electronic speckle pattern interferometry (ESPI), also called TV holography, is a non-contact optical metrology technique that measures surface displacement and deformation from laser speckle, developed from 1971 onward.

Electronic transition moment

The electronic transition moment is the matrix element of the electric dipole moment operator between two electronic states, determining whether a transition is allowed and how intense its absorption or emission line is.

Electronically activated recorder

The electronically activated recorder (EAR) is a psychology research method developed by Matthias Mehl and James Pennebaker in which participants wear a recorder that periodically samples ambient sound.

Electrons on helium

Electrons on helium are electrons trapped a few nanometers above liquid helium by their image charge, forming a clean two-dimensional electron gas studied since the 1970s and proposed in 1999 as a quantum computing platform.

Electronvolt

The electronvolt (eV), or megaelectronvolt scale unit, is a non-SI energy unit equal to exactly 1.602176634 × 10⁻¹⁹ joule, standard in atomic, nuclear, and particle physics.

Electroorganic synthesis

Electroorganic synthesis is the use of electron transfer at electrodes to drive organic reactions, replacing stoichiometric chemical oxidants and reductants with electrical current, often under mild conditions.

Electroosmotic flow

Electroosmotic flow (EOF) is the motion of an electrolyte solution past a charged solid surface under an applied electric field, a standard pumping method in microfluidics.

Electrophile

An electrophile, from "electron-loving," is a reagent that accepts both bonding electrons from its reaction partner, the nucleophile. Electrophiles are Lewis acids and organize most of polar organic chemistry.

Electrophilic addition

Electrophilic addition is an organic reaction in which an electrophile adds across the double or triple bond of an unsaturated molecule, the characteristic reaction class of alkenes.

Electrophilic amination

Electrophilic amination is a synthetic organic chemistry method forming carbon–nitrogen bonds by transferring an electrophilic amino group to organometallic compounds or enolates, inverting usual amine-synthesis polarity.

Electrophilic aromatic substitution

Electrophilic aromatic substitution is an organic reaction in which an electrophile replaces a hydrogen atom on an aromatic ring such as benzene, most often by halogenation, nitration, sulfonation, or Friedel–Crafts reactions.

Electrophilic fluorination

Electrophilic fluorination is a chemical synthesis method that transfers fluorine to electron-rich sites in organic molecules using reagents such as Selectfluor and NFSI, forming C–F, N–F, or O–F bonds in one step.

Electrophilic halogenation

Electrophilic halogenation is an electrophilic aromatic substitution in which bromine or chlorine replaces hydrogen on an aromatic ring, using a Lewis acid catalyst such as FeBr₃.

Electrophilic substitution

Electrophilic substitution is an organic reaction in which an electrophile replaces a hydrogen on an aromatic ring, installing halogen, nitro, sulfonic acid, alkyl, or acyl groups.

Electrophilicity index

The electrophilicity index (ω) is a reactivity descriptor from conceptual DFT, defined by Parr, von Szentpály, and Liu in 1999 as electronegativity squared divided by twice chemical hardness.

Electrophoresis

Electrophoresis, also called ionophoresis, is a laboratory technique in which charged molecules such as DNA, RNA, and proteins migrate in an electric field, separating mixtures by size and charge.

Electrophoretic deposition

Electrophoretic deposition, also called electrophoretic painting or electro-coating, deposits charged particles suspended in a liquid onto an electrode under an applied electric field, forming coatings or solid bodies.

Electrophoretic light scattering

Electrophoretic light scattering is an optical characterization technique that measures the electrophoretic mobility of dispersed particles by detecting the Doppler shift of scattered laser light, yielding zeta potential, a standard indicator of colloidal stability.