Chemistry Terms Starting with the Letter E

Chemistry Glossary and Dictionary

E is for element, such as gallium.
E is for element, such as gallium. Foobar, wikipedia.org

This chemistry glossary offers definitions for terms which are commonly used in chemistry and chemical engineering. These are words that start with the letter E.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

earths - Earths is an alchemical and old chemical term for compounds were thought to be elements but were later discovered to be metal oxides.

ebullition - a phase transition from the liquid state to the gas state, usually occurring when a liquid is heated to its boiling point.

 Also Known As: boiling
Example: boiling is seen when water is heated until it forms steam

EC

eclipsed conformation - Eclipsed conformation is the conformation that occurs when the dihedral angle between two atoms or groups of atoms is 0°. The atoms or groups of atoms around the single bond align with each other where they would overlap or eclipse each other if viewed along the axis of rotation.

effective nuclear charge

effervescence

efflorescence

effusion

Einstein's equation - the relation ΔE = Δmc2, relating energy and mass changes, where E is energy, m is mass, and c is the speed of light.

einsteinium - Einsteinium is the name for the element with atomic number 99 and is represented by the symbol Es. It is a member of the actinide group.

elastic - A substance is elastic if substance returns to its original shape after being deformed.

elasticity

elastic limit - Elastic limit is the maximum amount of force that can be applied to a substance before it is no longer elastic.

elastomer - An elastomer is a polymer that can be stretched and returns to its original shape without permanent deformation. Example: Natural rubber is an elastomer.

electric circuit - A circuit is a closed path through which electric current can flow. The current can flow in the form of free electrons or as ions.

Also Known As: electric circuit, electrical circuit

electrical conductivity

electrical resistivity

electric dipole - An electric dipole is formed when the centers of positive charges and negative charges do not coincide. Example: Polar molecules are electric dipoles.

electric field - An electric field is a field around charged particles and changing magnetic fields which exerts a force on charges within the field. Electric field is defined as the electrical force expressed on a stationary positive charge.

electrochemical cell

electrochemistry

electromotive force - emf

electrode

electrode potential - Electrode potential is the potential difference between the electrode and its solution.

electrokinetic potential - The electrokinetic potential is defined as the potential difference across phase boundaries between solids and liquids. In colloids, electrokinetic potential is the electric potential difference across the ionic layer around a charged colloid ion. Typically, the higher the electrokinetic potential, the more stable the colloid. When the zeta-potential equals zero, the colloid will precipitate into a solid. Also Known As: zeta potential

electrolysis

electrolyte

electrolytic cell

electromagnetic radiation

electron

electron affinity

electron capture

electron cloud

electron configuration

electron density

electron domain

electronegativity

electron pair - An electron pair is a pair of electrons in one orbital which have opposite spins or a pair of electrons in a covalent or coordinate bond.

electron pair repulsion

electron-sea model

electron shell - An electron shell is a set of atomic electrons grouped together by their quantum energy levels.

electron spin

electron volt - The electron volt is a unit of energy. One electron volt (eV) is equal to the change in energy as an unbound electron passes through a potential difference of one volt. 1 eV = 1.602176487(40)x10−19 J

electrophile

electroplating

electrostatic forces

electrum

element

elementary reaction

element symbol

ELF - ELF is an acronym for Extremely Low Frequency.

In general, ELF refers to part of the electromagnetic spectrum with frequencies from 1 to 300 Hz. In radio and atmospheric studies, ELF refers to radio waves with frequencies between 30 and 3000 Hz. Also Known As: extremely low frequency

elimination reaction - An elimination reaction is a type of chemical reaction where a reactant loses atoms or groups of atoms and forms a double bond.

embrittlement - Embrittlement is the loss of ductility through a chemical or physical change. Example: Freezing fruit with liquid nitrogen is an example of embrittlement.

emissions

emission spectrum

emissivity - Emissivity is the ratio of energy emitted by a material to the energy emitted by a black body at the same temperature. Emissivity values range from 0 to 1. The 'shinier' an object is, the lower the emissivity. Dark objects have emissivity values closer to 1.

empirical formula

emulsifier

emulsion

enantiomer

endergonic - Endergonic refers to a chemical reaction where the free energy of the system increases. Endergonic reactions absorb energy from their surroundings and are not spontaneous.

endothermic

enediol

energy

energy density - Energy density is the amount of energy stored or available by a system per unit volume.

engineering - Engineering is the application of scientific principles to design or develop structures, equipment, or processes. The main branches of engineering include electrical engineering, mechanical engineering, chemical engineering, civil engineering, aerospace engineering, automotive engineering, and computer engineering. A person who practices engineering is called an engineer.

enol - An enol is an alkene where a hydroxyl group is attached to one of the double bonded carbonatoms. Example: Butenol is an enol. The hydroxyl group is attached to the third carbon of the alkene chain.

enolate - An enolate is an anion formed when a hydrogen atom is removed from the hydroxyl group of an enol.

enriched uranium - Enriched uranium is a sample of uranium where the abundance of the isotope U-235 is increased above the natural abundance.

 Examples: Nuclear reactors need U-235 to produce a controlled nuclear chain reaction. Natural uranium contains only 0.7% U-235. Nuclear reactor fuel is typically enriched to contain approximately 5% U-235.

enthalpy

enthalpy change

enthalpy of atomization

enthalpy of fusion - Enthalpy of fusion is the change in enthalpy when a solid is melted into a liquid. Also Known As: heat of fusion. Example: The enthalpy of fusion for water is 334 kJ/kg or 79.72 calories/gram.

enthalpy of reaction

enthalpy of vaporization - Enthalpy of vaporization is the change in enthalpy when a liquid is converted to a gas at constant pressure. Enthalpy of vaporization is denoted by the symbol ΔHvap. Also Known As: heat of vaporization. Example: The enthalpy of vaporization of water is 2257 kJ/kg.

entropy

enzyme - An enzyme is a protein that functions as a catalyst for a chemical reaction.

epsom salt - Epsom salt is a common name for the compound magnesium sulfate, MgSO4.

equation of state - An equation of state is a relation between state variables. It is a thermodynamic equation which describes the state of matter under a given set of physical conditions, typically relating energy, temperature, volume, and pressure. Equations of state most commonly are used to describe the properties of fluids, such as liquids, gases, and plasma, though equations of state may also be applied to solids.
Also Known As: Equations of State, thermodynamic equations
Examples: Examples of equations of state include the Ideal Gas Law, Charles's Law, Dalton's Law of Partial Pressure

equilibrium - Equilibrium is the state of a reversible reaction where the forward reaction rate is equal to the reverse reaction's rate.

equilibrium concentration - Equilibrium concentration of a product or reactant is the concentration of an aqueous solution of the reactant or product when the reaction is at chemical equilibrium.

equilibrium constant

equivalence point

erbium - Erbium is element atomic number 68 on the periodic table.

erg - An erg is a CGS unit of energy.
1 erg = 1 dyne·cm = 1 g·cm2/s2.
1 erg = 10-7 Joules

essential amino acid

essential oil - An essential oil is a concentrated liquid containing the aroma compounds or terpenes of a plant.

ester

ether

ethyl group - The ethyl group is a alkyl functional group where one of the hydrogen atoms from the ethane molecule is removed. The molecular formula for the ethyl group is CH3CH2-.
Also Known As: -Et
Example: Ethylbenzene is a benzene ring connected to the ethyl group.

europium - Europium is the name for the element with atomic number 63 and is represented by the symbol Eu. It is a member of the lanthanide group.

eutectic

evaporation

exa - Exa is the prefix associated with 1018 and is denoted by the symbol E.

excess reactant

excited state

exergonic

exothermic

exothermic reaction

experimental yield - Experimental yield is the measured amount of product produced in a reaction.

extensive property

extinction

extinction coefficient

extremely low frequency radiation - Extremely Low Frequency radiation refers to the part of the electromagnetic spectrum with frequencies between 1 and 300 Hz.
For radio communications and atmospheric studies, the extremely low frequency range is between 30 and 3000 Hz.
Also Known As: ELF

E-Z notation

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z