Glossary of chemistry terms

Chemistry

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This page is a glossary of chemistry terms. Chemistry has an extensive vocabulary and a significant amount of jargon. 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

Contents: 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— See also

A

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
activation energy
activity series
actual yield
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
anode
aromaticity - chemical property of conjugated rings that results in unusual stability. See also benzene.
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 mass unit
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
average atomic mass
Avogadro's law
Avogadro's number

B

barometer -
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
boiling point -
boiling-point elevation -
bond - the attraction and repulsion between atoms and molecules that is a cornerstone of chemistry
Boyle's law -
Brønsted-Lowrey acid -
Brønsted–Lowry acid–base reaction -
Brønsted-Lowrey base -
buffered solution -
burette (also buret) - glassware used to dispense specific amounts of liquid when precision is necessary (e.g. titration and resource dependent reactions)

C

catalyst - a chemical compound used to change the rate (either to speed up or slow down) of a reaction, but is regenerated at the end of the reaction.
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

D

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

E

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
enthalpy - measure of the total energy of a thermodynamic system (usually symbolized as H)
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

F

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
- the mass of a substance altered at an electrode during electrolysis is directly proportional to the quantity of electricity transferred at that electrode
- 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

G

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
Gibbs energy - value that indicates the spontaneity of a reaction (usually symbolized as G)

H

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

J

jodium – Latin name of the halogen element iodine

I

indicator - a special compound added to solution that changes color depending on the acidity of the solution; different indicators have different colors and effective pH ranges
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.

K

Kinetics - A sub-field of chemistry specializing in reaction rates
Kinetic energy - The energy of an object due to its motion.

L

lanthanides - Elements 57 through 71
lattice - Unique arrangement of atoms or molecules in a crystalline liquid or solid.
Laws of thermodynamics
liquid - A state of matter which takes the shape of its container
light - Portion of the electromagnetic spectrum which is visible to the naked eye. Also called "visible light."
London dispersion forces - A weak intermolecular force

M

Metal - Chemical element that is a good conductor of both electricity and heat and forms cations and ionic bonds with non-metals.
melting - The phase change from a solid to a liquid
metalloid - A substance possessing both the properties of metals and non-metals
methylene blue - a heterocyclic aromatic chemical compound with the molecular formula C₁₆H₁₈N₃S Cl
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
- 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)

N

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
nuclear magnetic resonance spectroscopy - technique that exploits the magnetic properties of certain nuclei, useful for identifying unknown compounds
number density – a measure of concentration of countable objects (atoms, molecules, etc.) in space; number per volume

O

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

P

pH - the measure of acidity (or basicity) of a solution
plasma - state of matter similar to gas in which a certain portion of the particles are ionized
poor metal - Metallic elements in the p-block, characterized by lower melting and boiling points than other metals
potential energy - energy stored in a body or in a system due to its position in a force field or due to its configuration
precipitate - formation of a solid in a solution or inside another solid during a chemical reaction or by diffusion in a solid
precision - How close the results of multiple experimental trials are. See also accuracy.
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 - the addition of a proton (H⁺) to an atom, molecule, or ion

Q

Quantum mechanics - the study of how atoms, molecules, subatomic particles, etc. behave and are structured
quarks - elementary particle and a fundamental constituent of matter

R

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

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 (Energy_rest = 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

T

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
transuranic element - element with atomic number greater than 92; none of the transuranic elements are stable
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

U

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))

V

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

W

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

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

Y

yield - the amount of product produced during a chemical reaction

Z

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

External links

IUPAC Compendium of Chemical Terminology