- a solid melts: when the organization of its particles breaks down
- A substance may change from one state to another after a change in...: temperature
- all crystals have sides: that intersect at angles and are characteristic for a given substance
- allotropes: two or more different molecular forms of the same element in the same physical state
- amorphous solid: lack an ordered internal structure
- barometer: measures atmospheric pressure
- crystal systems: seven groups into which all crystals may be classified
- evaporation: when vaporizationoccurs at the surface of a liquid that is not boiling
- Evaporization is a cooling process: particles in a liquid with the highest kinetic energy tend to escape first, leaving the remaining particles with a lower average kinetic energy and a lower temperature
- gas molecules: far apart
- gas pressure: the force exerted by a gas per unit surface area of an object
- gravity: the force that hold air molecules in Earth's atmosphere
- kinetic energy: the energy an object has because of its motion
- kinetic theory on collisions of gas particles: perfectly elastic because kinetic energy is transferred without loss from one particle to another and the kinetic energy remains constant
- Liquid particles: free to slide past one another
- Liquids are much denser than gases: intermolecular forces reduce the amount of space between the particles in a liquid
- particles' arrangements in a crystal lattice: orderly, repeating, and three-dimensional patterns
- paths of gas particles: relatively short because they are constantly colliding with each other or other objects
- phase diagram: shows the conditions of temperature and pressure at which a substance exists as solid, liquid, and gas
- rhw triple pont of a substance: describes the only set of conditions at which all three phases cna exist in equilibrium with one another
- some substances decompose: when heated
- Standard Temperature and pressure(STP): the conditions under which the volume of a gas is usually measured
- the boiling point of a liquid: the temperature at which the vaor pressure of the liquid is just equal to the external pressure
- the motion of particles in solids: restricted to small vibrations about fixed points
- the temperature at whichthe liquid and solid states of a substance are in equilibrium is the same as: the melting and freezing point of the substance
- vaporization: the conversion of a liquid into a gas
- when the temperature of a contained liquid increases: vapor pressure increases
- why solids have vapor pressure: some particles near the surface of a solidsubstance have enough kinetic energy directly into the vapor phase