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27.1: A

Difficulty Level: At Grade Created by: CK-12
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absolute zero
The temperature at which the motion of particles theoretically ceases.
accepted value
The true or correct value of a measurement based on general agreement with a reliable reference.
Measure of how close a measurement is to the correct or accepted value of the quantity being measured.
Molecular compound that contains one or more hydrogen atoms and produces hydrogen ions when dissolved in water.
acid ionization constant
The equilibrium constant for the ionization of an acid.
acidic solution
A solution in which the concentration of hydrogen ions is greater than the concentration of hydroxide ions.
A series of 14 elements from thorium (atomic number 90) to lawrencium (atomic number 103).
activated complex
An unstable arrangement of atoms that exists momentarily at the peak of the activation energy barrier.
activation energy
The minimum energy that colliding particles must have in order to undergo a reaction.
active site
The place on an enzyme where the substrate binds.
activity series
A list of elements in decreasing order of their reactivity.
actual yield
The amount of product that is formed when a reaction is carried out in the laboratory.
addition polymer
A polymer formed by chain addition reactions between monomers that contain a double bond.
addition reaction
A reaction in which an atom or molecule is added to an unsaturated molecule, making a single product.
An organic compound that contains one or more hydroxyl (−OH) groups.
An organic compound in which a carbonyl group (C=O) is attached to a carbon atom at the end of a carbon chain.
aliphatic hydrocarbon
A hydrocarbon that does not contain the benzene group or benzene ring.
A hydrocarbon in which there are only single covalent bonds.
A hydrocarbon with one or more carbon-carbon double covalent bonds.
alkyl group
A hydrocarbon substituent.
alkyl halide
An organic compound in which one or more halogen atoms are substituted for one or more hydrogen atoms in a hydrocarbon.
A hydrocarbon with one or more carbon-carbon triple covalent bonds.
A mixture composed of two or more elements, at least one of which is a metal.
alpha particle (α)
A helium nucleus, two protons and two neutrons, which is emitted during some types of radioactive decay.
alkali metal
Element in Group 1 (lithium, sodium, potassium, rubidium, cesium, and francium).
alkaline earth metal
Element in Group 2 (beryllium, magnesium, calcium, strontium, barium, and radium).
An organic compound that can be considered to be a derivative of ammonia (NH3).
amino acid
A compound that contains both an amino group (−NH2) and a carboxyl group (−COOH) in the same molecule.
amorphous solid
Solid that lacks an ordered internal structure.
A substance that is capable of acting as either an acid or a base by donating or accepting hydrogen ions.
analytical chemistry
Branch of chemistry that is the study of the composition of matter, focusing on separating, identifying, and quantifying chemicals in samples of matter
angular momentum quantum number
Indicates the shape of the orbital, symbolized by the letter l.
A negatively charged ion.
The electrode at which oxidation occurs.
applied chemistry
Chemistry that is directed towards a specific practical goal or application.
aqueous solution
Water that contains one or more dissolved substances.
aromatic hydrocarbon
A hydrocarbon that contains one or more benzene rings.
Arrhenius acid
A compound which ionizes to yield hydrogen ions (H+) in aqueous solution.
Arrhenius base
A compound which ionizes to yield hydroxide ions (OH) in aqueous solution.
artificial transmutation
The bombardment of stable nuclei with charged or uncharged particles in order to cause a nuclear reaction.
atmospheric pressure
The pressure exerted by gas particles in Earth’s atmosphere as those particles collide with objects.
Smallest particle of an element that retains the properties of that element.
atomic emission spectrum
Pattern of lines formed when light passes through a prism to separate it into the different frequencies of light it contains.
atomic mass
Weighted average of the atomic masses of the naturally occurring isotopes of that element.
atomic mass unit
Defined as a mass equal to one twelfth the mass of an atom of carbon-12.
atomic model
Way of accurately representing the experimental evidence about atoms in the simplest way possible.
atomic number (Z)
Number of protons in the nucleus of each atom.
atomic radius
One-half the distance between the nuclei of identical atoms that are bonded together.
Aufbau principle
States that an electron occupies orbitals in order from lowest energy to highest.
Avogadro’s hypothesis
Equal volumes of all gases at the same temperature and pressure contain equal numbers of particles.
Avogadro’s law
Gas law which states that the volume of a gas is directly proportional to the number of moles of gas when the temperature and pressure are held constant.
Avogadro’s number
The number of representative particles in a mole of any substance; numerical value is 6.02 × 1023.

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Date Created:
Apr 20, 2012
Last Modified:
Sep 06, 2016
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