 | Term | Definition |
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A substance may change from one state to another after a change in... |
temperature |
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kinetic energy |
the energy an object has because of its motion |
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gas molecules |
far apart |
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paths of gas particles |
relatively short because they are constantly colliding with each other or other objects |
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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 |
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gas pressure |
the force exerted by a gas per unit surface area of an object |
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gravity |
the force that hold air molecules in Earth's atmosphere |
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barometer |
measures atmospheric pressure |
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Standard Temperature and pressure(STP) |
the conditions under which the volume of a gas is usually measured |
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Liquids are much denser than gases |
intermolecular forces reduce the amount of space between the particles in a liquid |
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Liquid particles |
free to slide past one another |
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vaporization |
the conversion of a liquid into a gas |
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evaporation |
when vaporizationoccurs at the surface of a liquid that is not boiling |
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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 |
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when the temperature of a contained liquid increases |
vapor pressure increases |
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the boiling point of a liquid |
the temperature at which the vaor pressure of the liquid is just equal to the external pressure |
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the motion of particles in solids |
restricted to small vibrations about fixed points |
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a solid melts |
when the organization of its particles breaks down |
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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 |
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some substances decompose |
when heated |
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particles' arrangements in a crystal lattice |
orderly, repeating, and three-dimensional patterns |
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all crystals have sides |
that intersect at angles and are characteristic for a given substance |
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crystal systems |
seven groups into which all crystals may be classified |
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amorphous solid |
lack an ordered internal structure |
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allotropes |
two or more different molecular forms of the same element in the same physical state |
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phase diagram |
shows the conditions of temperature and pressure at which a substance exists as solid, liquid, and gas |
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rhw triple pont of a substance |
describes the only set of conditions at which all three phases cna exist in equilibrium with one another |
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why solids have vapor pressure |
some particles near the surface of a solidsubstance have enough kinetic energy directly into the vapor phase |
