Kinetic Theory States of Matter –Kinetic Molecular Theory –Four States of Matter –Thermal Expansion Chapter 16 Lesson 1

Kinetic Molecular Theory KMT KMT –Tiny, constantly moving particles make up all matter. –The kinetic energy (motion) of these particles increases as temperature increases. –These particles are colliding with each other and the walls of their container.

Four States of Matter Solids Solids –low KE - particles vibrate but can’t move around –atoms held tightly into place –definite shape & volume

Four States of Matter Liquids Liquids –higher KE - particles can move around but are still close together –indefinite shape –definite volume

Four States of Matter Gases Gases –high KE - particles can separate and move throughout container –indefinite shape & volume –move more quickly than particles that make up solids

Four States of Matter Plasma Plasma –very high KE - particles collide with enough energy to break into charged particles (+/-) –gas-like, indefinite shape & volume –stars, fluorescent light bulbs, TV tubes

Phase Changes Heat of fusion-melting Heat of fusion-melting –solid to liquid. –energy required to change a substance from the solid phase to the liquid phase at its melting point is known as the –some attractive forces are broken Freezing Freezing –liquid to solid melting point = freezing point

Phase Changes Heat of vaporization Heat of vaporization –energy required for the liquid at its boiling point to become a gas. –all attractive forces are broken –EX: steam burns, sweating, and… the drinking bird

Heating Curves Evaporation Evaporation –liquid to gas below the boiling point Condensation Condensation –gas to liquid

Heating Curves Solid - KE  Melting - PE  Liquid - KE  Boiling - PE  Gas - KE 

Phase Changes Sublimation Sublimation –solid to gas –EX: dry ice, freeze drying, iodine

Phase Changes

Thermal Expansion Most matter expands when heated & contracts when cooled. Most matter expands when heated & contracts when cooled.  Temp causes  KE. Particles collide with more force & spread out.  Temp causes  KE. Particles collide with more force & spread out. EX: thermostats (bimetallic strip) EX: thermostats (bimetallic strip)

Heating Curves Kinetic Energy Kinetic Energy –motion of particles –related to temperature Potential Energy Potential Energy –space between particles –related to phase changes

Solid or a Liquid? Amorphous solids and liquid crystals –two classes of materials don’t react as expected when changing states. –solids soften and gradually turn into a liquid over a temperature range –lack the highly ordered structure found in crystals –are typically long, chainlike structures that can get jumbled and twisted

The Strange Behavior of Water Water molecules –unusual in that they have highly positive and highly negative areas –charged regions affect its behavior –as the temp drops the particles move closer together

The Strange Behavior of Water Freezing water molecules –unlike charges are attracted to each other and line up so that only positive and negative zones are near each other. –water molecules orient themselves according to charge, empty spaces occur in the structure. –these empty spaces are larger in ice than in liquid water, so water expands when going from a liquid to a solid state.

Liquid Crystals LCD –flow during the melting phase similar to a liquid, but they do not lose their ordered arrangement completely. –placed in classes depending upon the type of order they maintain when they liquefy –are highly responsive to temperature changes and electric fields. –ex: televisions, watches, clocks, and calculators