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# 26.1: A

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absolute zero
the temperature at which molecules stop moving and therefore have zero kinetic energy
accuracy
reflects how close the measured value is to the actual value
acidic salt
a salt formed in a neutralization reaction between a strong acid and a weak base
actinide series
elements with atomic numbers 89 – 102
activation energy
the minimum amount of energy that needs to be supplied to the system so that a reaction can occur
activated complex
a high energy transitional structure that exists just after the bonds in the reactants are broken and before the products are formed
group of un-bounded particles that exist right after the bonds in the reactant have been broken and before the product bonds have formed
actual yield
the actual amount of product that is formed in the laboratory experiment
alcohol
an organic compound that contains the hydroxyl (-OH) group
aldehyde
an organic compound that contains a terminal carbonyl group
alkali metals
Group 1A of the periodic table
alkaline earth metals
Group 2A of the periodic table
alkane
a hydrocarbon containing only single bonds
alkene
a double bond between two carbon atoms, or a hydrocarbon containing a carbon-carbon double bond
alkyne
a triple bond between two carbon atoms, or a hydrocarbon containing a carbon-carbon triple bond
allotropes
different forms of a pure element caused by different bonding arrangements
alloy
a substance with metallic properties composed of a mixture of two or more elements
alpha decay
a common mode of radioactive decay in which a nucleus emits an alpha particle (a helium-4 nucleus)
alpha particle
a helium-4 nucleus
amino acid
a molecule that contains an amine group $(-\mathrm{NH}_2)$ and a carboxyl group $(-\mathrm{COOH}$)
amphoteric
a substance that acts as both acids and bases in reactions
amplitude (of a wave)
the “height” of a wave
angular momentum quantum number
a number that describes the sub-shell in which an electron can be found
anion
a negative ion
anode
the electrode at which oxidation occurs
Arrhenius acid
a substance that produces H+ ions in solution
Arrhenius base
a substance that produces OH- ions in a solution
induced radioactivity that is produced by bombarding an element with high-velocity particles
atmosphere
unit of pressure equivalent to the pressure under standard conditions at sea level and to 760 mm of Hg
atom
the basic building block of all matter
atomic mass
the weighted average of the masses of the naturally occurring isotopes of an element
atomic mass unit (amu)
used to express atomic and molecular masses, it is the approximate mass of a hydrogen atom, a proton, or a neutron and is one-twelfth of the mass of an unbound carbon-12 atom at rest; it is equivalent to the dalton
atomic number
the number of protons in the nucleus of an atom
one-half the distance between the centers of a homonuclear diatomic molecule
atomos
Democritus’s word for the tiny, indivisible, solid objects that he believed made up all matter in the universe
Aufbau principle
states that as electrons are added to “build up” the elements, each electron is placed in the lowest energy orbital available
autoionization
when the same reactant acts as both the acid and the base
describes the relationship between the volume and the number of moles of gas
the number of objects in a mole; equal to $6.02 \times 10^{23}$

Feb 23, 2012

Aug 01, 2014