allotrope
one of two or more different molecular forms of an element in the same physical state
amorphous solid
describes a solid that lacks an ordered internal structure; denotes a random arrangment of atoms
atmospheric pressure
the pressure exerted by atoms and molecules in the atmosphere surrounding Earth, resulting from collisions of these particles with objects
barometer
an instrument used to measure atmospheric pressure
boiling point (bp)
the temperature at which the vapor pressure of a liquid is just equal to the external pressure on the liquid
crystal
a solid in which the atoms, ions, or molecules are arranged in an orderly, repeating, three-dimensional pattern called a crystal lattice
evaporation
vaporization that occurs at the surface of a liquid that is not boiling
gas pressure
results from the force exerted by a gas per unit surface area of an object; due to the collisions of gas particles with the object
glass
transparent fusion product of inorganic materials that have cooled to a rigid state without crystallizing
kinetic energy
the energy an object has because of its motion
kinetic theory
a theory explaining the states of matter, based on the concept that all matter consists of tiny particles that are in constant motion
melting point (mp)
the temperature at which a substance changes from a solid to a liquid
normal boiling point
the boiling point of a liquid at a pressure of 101.3 kPa or 1 atm
pascal (Pa)
the SI unit of pressure
phase diagram
a graph showing the conditions at which a substance exists as a solid, liquid, or vapor
standard atmosphere (atm)
a unit of pressure; it is the pressure required to support 760 mm of mercury in a mercury barometer at 25C
sublimation
the process in which a solid changes to a gas or vapor without passing through the liquid stage
triple point
the point of a phase diagram that represents the only set of conditions at which all three phases exist equilibrium with one another
unit cell
the smallest group of particles within a crystal that retains the geometric shape of the crystal
vacuum
a space where no particles of matter exist
vaporization
the conversion of a liquid to a gas or a vapor
vapor pressure
a measure of the force exerted by a gas above a liquid in a sealed container