26.1. A http://www.ck12.org
26.1 A
absorption
Interaction of light with matter in which the particles of matter absorb light energy so light neither reflects
from nor passes through matter.
acceleration
Measure of the change in velocity of a moving object.
accuracy
Closeness of a measurement to the true value.
acid
Ionic compound that produces positive hydrogen ions (H+) when dissolved in water.
acidity
Concentration of hydrogen ions in a solution.
activation energy
Energy needed to start a chemical reaction.
alkali metal
Metal in group 1 of the periodic table that has one valence electron and is highly reactive.
alkaline Earth metal
Metal in group 2 of the periodic table that has two valence electrons and is very reactive but less so than an
alkali metal.
alkane
Saturated hydrocarbon that contains only single bonds between carbon atoms.
alkene
Unsaturated hydrocarbon that contains at least one double bond between carbon atoms.
alkyne
Unsaturated hydrocarbon that contains at least one triple bond between carbon atoms.
alloy
Mixture of a metal with one or more other elements.
alternating current (AC)
Electric current that keeps reversing the direction in which the current flows.
Amonton’s law
Gas law stating that, if the volume of a gas is held constant, increasing the temperature of the gas increases its
pressure.
Archimedes’ law (or principle)
Law stating that the buoyant force acting on an object equals the weight of the fluid displaced by the object.
aromatic hydrocarbon
Unsaturated cyclic hydrocarbon that has a strong aroma and alternating single and double bonds between
carbon atoms.
atom
Smallest particle of an element that still has the element’s properties.
atomic mass unit (amu)
SI unit for the mass of an atom, where 1 amu = the mass of a proton (about 1.7× 10 −^24 g).
atomic number
Number of protons in an atom.