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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Glossary of chemistry terms | 19/20 | https://en.wikipedia.org/wiki/Glossary_of_chemistry_terms | reference | science, encyclopedia | 2026-05-05T07:59:20.572989+00:00 | kb-cron |
triple bond A bond that involves the covalent sharing of three pairs of electrons (for example, the diatomic nitrogen molecule, N2, is composed of two nitrogen atoms linked by a triple bond).
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 or suspended particles.
== U ==
UN number A four-digit code used to note hazardous and flammable substances.
uncertainty The notion 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 crystalline lattice.
unit factor Statements used in converting between units.
unpaired electron
== V ==
vacuum flask Also Dewar flask or thermos. A storage vessel consisting of two flasks or other containers, placed one within the other and joined at the neck, and a space in between that is partially evacuated of air, creating a near-vacuum that significantly reduces the transfer of heat between the vessel's interior and its ambient environment. Vacuum flasks can greatly lengthen the time over which their contents remain warmer or cooler than the ambient environment.
valence electron Any of 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.
valency The combining capacity of an element.
van der Waals force One of the forces (attraction/repulsion) between molecules.
van 't Hoff factor The 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.
vapor pressure Also equilibrium vapor pressure. The pressure exerted by a vapor which is in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. It is commonly described as the tendency of particles to spontaneously escape from the liquid or solid state into the gaseous state and is used as an indication of a liquid's evaporation rate.
vaporization Also boiling. The phase transition of a substance from a liquid to a gas.
vaporization point See boiling point.
viscosity A measure of the resistance of a liquid to flow.
volatility A material quality which describes how readily a substance vaporizes. At a given temperature and pressure, a substance with high volatility is more likely to exist as a gas, while a substance with low volatility is more likely to exist as a liquid or solid; equivalently, less volatile substances will more readily condense from a gaseous state than highly volatile ones.
volt (V) A derived unit of electric potential, electric potential difference, and electromotive force, defined as one joule of work per coulomb.
voltmeter An instrument that measures electrical cell potential.
volume The quantity of three-dimensional space enclosed by a closed surface, or the space that a substance (solid, liquid, gas, or plasma) or shape occupies or contains. The SI unit for volume is the cubic metre (m3).
volumetric analysis See titration.
volumetric flask
== W ==
watch glass A circular, concave piece of glass commonly used in chemistry laboratories as a working surface for various purposes, such as evaporating liquids, holding solids while they are being weighed, heating small amounts of a substance, or as a cover for a beaker.
water A polar inorganic compound with the chemical formula H2O that is a tasteless, odorless, and generally colorless liquid at standard temperature and pressure, though it also occurs naturally as a solid and a gas at the Earth's surface. It is the most abundant substance on Earth and therefore an integral component of virtually all chemical and biological systems. Water is often described as the "universal solvent" for its inherent ability to dissolve many substances.
water of crystallization Also water of hydration. Water molecules that are present inside crystals. Upon crystallization from water or aqueous solutions, many compounds incorporate water in the interstices of their crystalline frameworks; the water molecules are typically present in a stoichiometric ratio and may interact to varying degrees with the atoms of the crystal.
wave function A mathematical function describing the position of an electron within a three-dimensional space.
weak acid An acid that only partially dissociates when dissolved in a solvent because, according to the reaction
HA
↽
−
−
⇀
H
+
+
A
−
{\displaystyle {\ce {HA <=> H+ + A-}}}
, equilibrium is reached while the concentration of the undissociated species
HA
{\displaystyle {\ce {HA}}}
is still significant; an example is acetic acid (CH3COOH). Contrast strong acid.
weak base
wet chemistry Also bench chemistry or classical chemistry. A form of analytical chemistry which uses classical laboratory methods such as simple observation and elementary chemical tests to study chemicals and chemical reactions, i.e. without the use of sophisticated instruments or automated or computerized analysis. It is often used in schools to teach the principles of chemistry to students.
wetting agent
work
work-up The series of manipulations required to isolate and purify the desired product or products of a chemical reaction.
== X ==
X-ray A form of ionizing, electromagnetic radiation between gamma and ultraviolet rays in the electromagnetic spectrum.
X-ray diffraction A laboratory method for establishing the structure of a crystalline solid by directing single wavelength X-rays at the solid and analyzing the resulting diffraction pattern.
X-ray photoelectron spectroscopy A spectroscopic technique used to measure the chemical composition of a material.
== Y ==
yield The quantifiable amount of product produced during a chemical reaction.
== Z ==
zero-point energy (ZPE)