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Glossary of chemistry terms

This page is a glossary of chemistry terms. Chemistry has an extensive vocabulary and a significant amount of jargon that are commonly used by chemists and in chemistry literature. This is a list of chemical terms, including laboratory tools, glassware, and equipment. Chemistry itself is a physical science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions.
Note: All periodic table references refer to the IUPAC Style of the Periodic Table


* absolute zero - a theoretical condition concerning a system at zero Kelvin where a system does not emit or absorb energy (all atoms are at rest)
* accuracy - how close a value is to the actual or true value; also see precision
* acid - a compound that, when dissolved in water, gives a pH of less than 7.0 or a compound that donates a hydrogen ion
* acid anhydride - a compound with two acyl groups bound to a single oxygen atom
* acid dissociation constant - an equilibrium constant for the dissociation of a weak acid
* actinides - the fifteen chemical elements that are between actinium (89) and lawrencium (103)
* activated complex - a structure that forms because of a collision between molecules while new bonds are formed
* addition reaction - within organic chemistry, when two or more molecules combine to make a larger one
* aeration - the mixing of air into a liquid or solid
* alkali metals - the metals of Group 1 on the periodic table
* alkaline earth metals - the metals of Group 2 on the periodic table
* allomer - a substance that has different composition than another, but has the same crystalline structure
* allotropy - elements that can have different structures (and therefore different forms), such as Carbon (diamonds, graphite, and fullerene)
* anion - negatively charge ions
* atom - a chemical element in its smallest form, and is made up of neutrons and protons within the nucleus and electrons circling the nucleus
* atomic number - the number representing an element which corresponds with the number of protons within the nucleus
* atomic orbital - the region where the electron of the atom may be found


* base - a substance that accepts a proton and has a high pH; a common example is sodium hydroxide (NaOH)
* biochemistry - the chemistry of organisms
* boiling - the phase transition of liquid vaporizing
* bond - the attraction and repulsion between atoms and molecules that is a cornerstone of chemistry
* burette (also buret) - glassware used to dispense specific amounts of liquid when precision is necessary (e.g. titration and resource dependent reactions)


* cation - positively charged ion
* centrifuge - equipment used to separate substances based on density by rotating the tubes around a centred axis
* cell potential - the force in a galvanic cell that pulls electron through reducing agent to oxidizing agent
* Chemical Law - certain rules that pertain to the laws of nature and chemistry - examples
* chemical reaction - the change of one or more substances into another or multiple substances
* colloid - mixture of evenly dispersed substances, such as many milks
* combustion - an exothermic reaction between an oxidant and fuel with heat and often light
* compound - a substance that is made up of two or more chemically bonded elements
* condensation - the phase change from gas to liquid
* conductor - material that allows electric flow more freely
* covalent bond - chemical bond that involves sharing electrons
* crystal - a solid that is packed with ions, molecules or atoms in an orderly fashion
* cuvette - glassware used in spectroscopic experiments. It is usually made of plastic, glass or quartz and should be as clean and clear as possible


* deionization - the removal of ions, and in water's case mineral ions such as sodium, iron and calcium
* deliquescence - substances that absorb water from the atmosphere to form liquid solutions
* deposition - settling of particles within a solution or mixture
* dipole - electric or magnetic separation of charge
* dipole moment - the polarity of a polar covalent bond
* dissolution or solvation - the spread of ions in a solvent
* double bond - sharing of two pairs of electrons


* earth metal - see alkaline earth metal
* electrolyte - a solution that conducts a certain amount of current and can be split categorically as weak and strong electrlytes
* electrochemical cell - using a chemical reaction's current, electromotive force is made
* electromagnetic radiation - a type of wave that can go through vacuums as well as material and classified as a self-propagating wave
* electromagnetism - fields that have electric charge and electric properties that change the way that particles move and interact
* electromotive force - a device that gains energy as electric charges pass through it
* electron - a subatomic particle with a net charge that is negative
* electron shells - an orbital around the atom's nucleus that has a fixed number electrons (usually two or eight)
* electric charge - a measured property (coulombs) that determine electromagnetic interaction
* element - an atom that is defined by its atomic number
* energy - A system's ability to do work
* entropy - the amount of energy not available for work in a closed thermodynamic system (usually symbolized as S)
* enzyme - a protein that speeds up (catalyses) a reaction
* eppendorf tube - generalized and trademarked term used for a type of tube; see microcentrifuge


* freezing - phase transition from liquid to solid
* Faraday constant - a unit of electrical charge widely used in electrochemistry and equal to ~ 96,500 coulombs.

It represents 1 mol of electrons, or the Avogadro number of electrons: 6.022 × 1023 electrons. F = 96 485.339 9(24) C/mol

* Faraday's law of electrolysis - a two part law that Michael Faraday published about electrolysis
o the mass of a substance altered at an electrode during electrolysis is directly proportional to the quantity of electricity transferred at that electrode
o the mass of an elemental material altered at an electrode is directly proportional to the element's equivalent weight.
* frequency - number of cycles per unit of time. Unit: 1 hertz = 1 cycle per 1 second


* galvanic cell - battery made up of electrochemical with two different metals connected by salt bridge
* gas - particles that fill their container though have no definite shape or volume
* geochemistry - the chemistry of and chemical composition of the Earth


* halogens - Group 17 on the Periodic Table and are all non-metals


* inorganic compound - compounds that do not contain carbon, though there are exceptions (see main article)
* inorganic chemistry - a part of chemistry concerned with inorganic compounds
* International Union of Pure and Applied Chemistry (IUPAC) -
* insulator - material that resists the flow of electric current
* ion - a molecule that has gained or lost one or more electrons
* ionic bond - electrostatic attraction between oppositely charged ions
* ionization -The breaking up of a compound into separate ions.


* kinetic energy -


* lanthanides -
* lattice -
* Laws of thermodynamics -
* liquid -
* light -
* London dispersion forces -


* metal -
* melting -
* methylene blue - a heterocyclic aromatic chemical compound with the molecular formula C16H18N3SCl
* microcentrifuge - a small plastic container that is used to store small amounts of liquid
* mole - abbreviated mol - a measurement of an amount of substance; a single mole contains approximately 6.022×1023 units or entities
o a mole of water contains 6.022×1023 H2O molecules
* molecule - a chemically bonded number of atoms that are electrically neutral
* molecular orbital - region where an electron can be found in a molecule (as opposed to an atom)


* neutron - a neutral unit or subatomic particle that has no net charge
* neutrino - a particle that can travel at speeds close to the speed of light and are created as a result of radioactive decay
* nucleus - the centre of an atom made up of neutrons and protons, with a net positive charge
* noble gases - group 18 elements, those whose outer electron shell is filled
* non-metal - an element which is not metallic
* nuclear - of or pertaining to the atomic nucleus
* number density – a measure of concentration of countable objects (atoms, molecules, etc.) in space; number per volume


* orbital - may refer to either an atomic orbital or a molecular orbital
* organic compound - compounds that contain carbon
* organic chemistry - a part of chemistry concerned with organic compounds


* plasma -
* poor metal -
* potential energy
* precipitate -
* precision -
* photon - a carrier of electromagnetic radiation of all wavelength (such as gamma rays and radio waves)
* proton - a positive unit or subatomic particle that has a positive charge
* protonation -


* Quantum mechanics - the study of how atoms, molecules, subatomic particles, etc. behave and are structured
* quarks -
* quarts -


* radiation - energy in the form of waves or subatomic particles when there is a change from high energy to low energy states
* radioactive decay - the process of an unstable atomic nucleus losing energy by emitting radiation


* s-block elements - Group 1 and 2 elements (alkali and alkaline metals), which includes Hydrogen and Helium
* salts - ionic compounds composed of anions and cations
* salt bridge - devices used to connection reduction with oxidation half-cells in an electrochemical cell
* saline solution - general term for NaCl in water
* Schrödinger equation - quantum state equation which represents the behaviour of an election around an atom
* semiconductor - an electrically conductive solid that is between a conductor and an insulator
* single bond - sharing of one pair of electrons
* sol - a suspension of solid particles in liquid. Artificial examples include sol-gels.
* solid - one of the states of matter, where the molecules are packed close together, there is a resistance of movement/deformation and volume change; see Young's modulus
* solute - the part of the solution that is mixed into the solvent (NaCl in saline water)
* solution - homogeneous mixture made up of multiple substances. It is made up of solutes and solvents.
* solvent - the part of the solution that dissolves the solute (H2O in saline water)
* spectroscopy - study of radiation and matter, such as X-ray absorption and emission spectroscopy
* speed of light - the speed of anything that has zero rest mass (Energyrest = mc² where m is the mass and c is the speed of light)
* Standard conditions for temperature and pressure or SATP - a standardisation used in order compare experimental results (25 °C and 100.000 kPa)
* state of matter - matter having a homogeneous, macroscopic phase; gas, plasma, liquid, and solid are the most well known (in increasing concentration)
* sublimation - a phase transition from solid to gas
* subatomic particles - particles that are smaller than an atom; examples are protons, neutrons and electrons
* substance - material with definite chemical composition


* talc - a mineral representing the one on the Mohs Scale and composed of hydrated magnesium silicate with the chemical formula H2Mg3(SiO3)4 or Mg3Si4O10(OH)2
* temperature - the average energy of microscopic motions of particles
* theoretical yield - see yield
* theory - a model describing the nature of a phenomenon
* thermal conductivity - a property of a material to conduct heat (often noted as k)
* thermochemistry - the study of absorption/release of heat within a chemical reaction
* thermodynamics - the study of the effects of changing temperature, volume or pressure (or work, heat, and energy) on a macroscopic scale
* thermodynamic stability - when a system is in its lowest energy state with its environment (equilibrium)
* thermometer - device that measures the average energy of a system
* titration - the process of titrating one solution with another, also called volumetric analysis
* torr - a unit to measure pressure (1 Torr is equivalent to 133.322 Pa or 1.3158×10−3 atm
* transition metal - elements that have incomplete d sub-shells, but also may be referred to as the d-block elements
* triple bond - the sharing of three pairs of electrons within a covalent bond (example N2)
* triple point - the place where temperature and pressure of three phases are the same (Water has a special phase diagram)
* Tyndall effect - the effect of light scattering by colloidal (mixture where one substance is dispersed evenly through another) or suspended particles


* UN number - a four digit code used to note hazardous and flammable substances
* uncertainty - a characteristic that any measurement that involves estimation of any amount cannot be exactly reproducible
* Uncertainty principle - knowing the location of a particle makes the momentum uncertain, while knowing the momentum of a particle makes the location uncertain
* unit cell - the smallest repeating unit of a lattice
* unit factor - statements used in converting between units
* universal or ideal gas constant - proportionality constant in the ideal gas law (0.08206 L·atm/(K·mol))


* valence electron - the outermost electrons of an atom, which are located in electron shells
* Valence bond theory - a theory explaining the chemical bonding within molecules by discussing valencies, the number of chemical bonds formed by an atom
* van der Waals force - one of the forces (attraction/repulsion) between molecules
* van 't Hoff factor - ratio of moles of particles in solution to moles of solute dissolved
* vapor - when a substance is below the critical temperature while in the gas phase
* vapour pressure - pressure of vapour over a liquid at equilibrium
* vaporization - phase change from liquid to gas
* viscosity - the resistance of a liquid to flow (oil)
* volt - one joule of work per coulomb - the unit of electrical potential transferred
* voltmeter - instrument that measures the cell potential
* volumetric analysis - see titration


* water - H2O - a chemical substance, a major part of cells and Earth, and covalently bonded
* wave function - a function describing the electron's position in a three dimensional space
* work - the amount of force over distance and is in terms of joules (energy)


* X-ray - form of ionizing, electromagnetic radiation, between gamma and UV rays
* X-ray diffraction - a method for establishing structures of crystalline solids using singe wavelength X-rays and looking at diffraction pattern
* X-ray photoelectron spectroscopy - a spectroscopic technique to measure composition of a material


* yield - the amount of product produced during a chemical reaction


* zone melting - a way to remove impurities from an element by melting it and slowly travel down an ingot (cast)

See also
Chemistry portal

* List of chemical elements
* List of chemistry topics
* List of science topics
* The Standard Periodic Table
* Chemistry Mnemonics

External links

* IUPAC Compendium of Chemical Terminology

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