10.3 The Phases of Matter pp

10.3 The phases of matter On Earth, pure substances are usually found as solids, liquids, or gases. These are called phases of matter.

10.3 The phases of matter A solid holds its shape and does not flow. The molecules in a solid vibrate in place, but on average, don’t move far from their places.

10.3 The phases of matter A liquid holds its volume, but does not hold its shape—it flows. Liquids flow because the molecules can move around.

10.3 The phases of matter A gas flows like a liquid, but can also expand or contract to fill a container. A gas does not hold its volume. The molecules in a gas have enough energy to completely break away from each other.

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10.3 The phases of matter When they are close together, molecules are attracted through intermolecular forces.

10.3 The phases of matter The forces in chemical bonds are stronger than intermolecular forces.

10.3 Intermolecular forces Within all matter, there is a constant competition between temperature and intermolecular forces. When temperature wins the competition, molecules fly apart and you have a gas. When intermolecular forces win the competition, molecules clump tightly together and you have a solid.

10.3 Melting and boiling The melting point is the temperature at which a substance changes from a solid to a liquid.

10.3 Melting and boiling The temperature at which a liquid becomes a gas is called the boiling point.

Notice temperature is constant while ice melts!

10.3 Sublimation Sometimes a solid can change directly to a gas when heat energy is added. This process is called sublimation.

PLASMA The state of matter that does not have a definite shape or volume and whose particles have broken apart.

PLASMA (cont.) Natural plasmas are found in the Aurora Borealis. Artificial plasmas are found in fluorescent lighting.

Einstein-Bose Condensate The fifth phase of matter See videowww.brainPOP.com

BOSE-EINSTEIN CONDENSATE Bose-Einstein Condensate forms when a gas composed of certain particles, referred to as "bosonic particles," is cooled to below a critical temperature. At this temperature, the matter wavelength becomes so large that the wave-like atoms overlap and start to oscillate in concert, forming the condensate. This condensate consists of a macroscopic number of particles, all of which are in a single quantum state, known as the "ground state of the system." Bose- Einstein condensate is a phase transition governed by the wave nature of the particles, as opposed to interactions between them.

PHASE CHANGES EXOTHERMIC CHANGES – energy is released (energy exits) Freezing – liquid → solid condensation – gas → liquid deposition – gas → solid

PHASE CHANGES ENDOTHERMIC CHANGES - energy is added Melting – solid → liquid Sublimation – solid → gas vaporization – liquid → gas

2 KINDS OF VAPORIZATION Boiling - vaporization that occurs throughout a liquid. The boiling point is the temperature at which a liquid boils.

2 KINDS OF VAPORIZATION Evaporation– occurs at the surface of a liquid at a temperature below its boiling point. Perspiration is the cooling off of the body through evaporation.

SUMMARIZING THE CHANGES OF PHASE Change of StateDirectionEndothermic or exothermic Example MeltingSolid to liquidEndothermicice melts into liquid water at 0°C FreezingLiquid to solidExothermicLiquid water freezes into ice at 0°C VaporizationLiquid to gasEndothermicLiquid water vaporizes into steam at 100°C CondensationGas to liquidExothermicSteam condenses into liquid at 100°C SublimationSolid to gasEndothermicDry ice sublimes into a gas