States of Matter

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States of Matter

• D.L. Mowery
• Douglass High School

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The Kinetic Theory

• All matter is composed of small particles
• Atoms
• Molecules
• Ions
• They are in constant, random motion
• They constantly collide with each other and with
  the walls of their container

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Substances

• Elements- simplest kind of matter cannot be
  broken down any simpler all one kind of atom.
• Compounds are substances that can be broken down
  only by chemical methods
• When broken down, the pieces have completely
  different properties than the original compound.
• Made of two or more atoms, chemically combined
  (not physical blend!)

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Which is it?
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Phase Properties
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Other States

• Solids with particles in repeating geometric
  patterns are crystals
• Those with particles arranged randomly are
  amorphous
• Plasma
• Hot, ionized gas particles
• Electrically charged
• Most common state in universe

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Thermal Expansion

• Particles in any state expand when heated
  (generally)
• Examples of solids
• Expansion joints
• Power lines
• Thermostats
• Different materials expand at different rates

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Thermal Expansion

• Mercury and alcohol are liquids that expand in
  thermometers
• Air expands when heated (becoming less dense)
• Water reaches maximum density at about 4 C
• Ice particles are farther apart than liquid water
  (so it floats)

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Properties

• Physical Properties- can be observed and measured
  without changing composition
• Examples- color, hardness, m.p., b.p.
• Chemical Properties- can only be observed by
  changing the composition of the material

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Physical Changes

• Changes appearances, w/out changing composition.
• Ex. Boil, melt, cut, bend, split, crack
• Boiled water is still water.
• Chemical changes - a new form of matter is
  formed.
• Ex. Rust, burn, decompose, ferment

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Changes in State

• Melting - solid to liquid
• Particles get more kinetic energy and begin
  rotating around each other
• There isnt enough energy to break the
  inter-particular attractions, so the particles
  remain close (liquid)
• The energy required to melt a solid is called the
  heat of fusion

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Freezing - Liquid to Solid

• Particles lose kinetic energy and slow down
• Attractive forces between particles become
  stronger than the particles motion, so the
  particles begin merely vibrating in place
• The amount of heat the particles must lose to
  turn into a solid is called the heat of fusion

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Vaporization - Liquid to Gas

• Types
• Boiling - rapid gas bubbles are produced
  throughout
• Evaporation - slow occurs at the surface
• Liquid particles gain enough kinetic energy to
  overcome forces between the particles and they
  begin translational motion this energy is called
  the heat of vaporization

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Evaporation is a Cooling Process

• Particles in a liquid gain kinetic energy
• They leave as gas particles
• Taking the energy away with them
• This leaves less energy in the liquid, therefore
  cooling down what is left

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Condensation - Gas to Liquid

• Particles lose kinetic energy, slow down, and
  come closer together
• Inter-particular forces become strong enough to
  make particles merely rotate around each other
• The energy they lose to turn into a liquid is the
  heat of vaporization

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Sublimation

• Solid to gas or gas to solid
• Dry ice - carbon dioxide
• Iodine
• Frost
• During phase changes there is no change of
  temperature

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Properties of Fluids

• Archimedes Principle
• Fluids exert an upward force on objects
• It is called the buoyant force
• The buoyant force is equal to the weight of the
  fluid displaced

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If the weight of the displaced fluid equals the
weight of the object, the object floats.
Fbuoy
Fw Fbuoy
Object floats
Fw
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If the weight of the displaced water is less than
the weight of the object, the object sinks.
Fw gt Fbuoy
Fbuoy
Object sinks
Fw
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How can a steel ship float?

• The hull contains mostly air and displaces a lot
  of water...enough so that Fbuoy Fw and it
  floats.

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Density

• Mass of an object divided by the volume of the
  object
• Dm/v
• Substances with high density are typically
  heavier than those with lower densities
• High density substances will sink in low density
  liquids

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Chemical Reactions

• When one or more substances are changed into new
  substances
• Reactants- stuff you start with
• Products- What you make
• Ability to undergo chemical reaction is called a
  chemical property
• Products have NEW PROPERTIES
• Arrow from reactants to products

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Indications of a chemical reaction

• Energy absorbed or released (temperature changes
  hotter or colder)
• Color change
• Gas production (bubbling, fizzing, or odor
  change)
• Formation of a precipitate- a solid that
  separates from solution (wont dissolve)
• Irreversibility- not easily reversed

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The End.