Physical Science

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Physical Science

• Changes in Matter
• Benchmarks
• IV.2.MS.1
• IV.2.MS.2
• IV.2.MS.3

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Benchmarks

• Describe common physical changes in matter
  evaporation, condensation, thermal expansion,
  contraction.  (IV.2.MS.1)
• Describe common chemical changes in terms of
  properties of reactants and products. (IV.2.MS.2)
  
• Explain physical changes in terms of the
  arrangement and motion of atoms and molecules.
   (IV.2.MS.3)

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3 States of Matter

• There are 3 major states of matter, they are
• Solids
• Liquids
• Gasses
• In all three states of matter, molecules are in
  constant motion.

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And yet another phase of matter

• Plasma is another phase of matter that is
  sometimes recognized by scientists.
• It is a state above the gas phase.
• Click the link to see another explanation of the
  states of matter.
• http//www.chem4kids.com/files/matter_states.html

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Solids

• In a solid, relatively strong forces are exerted
  between the molecules, so the molecules of the
  material vibrate slowly.
• Solids, therefore, have a definite shape and
  volume.

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Liquids

• When heat energy is added, the molecules vibrate
  faster as they absorb the energy.
• At the melting temperature of the material, the
  molecules have gained enough energy, so that they
  can slip and slide past each other.
• The material is now a liquid.

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Gasses

• Liquids still have a definite volume, but take
  the shape of their container.
• When more heat energy is added, the motion of the
  molecules within the liquid increases, until some
  of the molecules overcome the forces, becoming a
  gas.
• The liquid has now evaporated to a gas.

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The reverse is also true

• Gas molecules are separated by relatively great
  distances and move about freely.
• Gases take the shape and volume of their
  container.
• Conversely, when enough energy is lost from gas
  molecules, they condense into the liquid phase.

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Condensation
Freezing
Contract
more heat energy less heat energy E


-E warmer colder
States of Matter
Plasma
BEC
Evaporation
Melting
Expand
10
Thermal Expansion

• As a solid is heated, particles move faster and
  faster and vibrate against each other with more
  force.
• As a result, the particles spread apart slightly
  in all directions and the solid expands.
• The same effect also occurs in liquids and gases.

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Thermal Expansion

• Almost all matter expands as it gets hotter and
  contracts as it cools.
• This characteristic of matter is called thermal
  expansion.
• This happens because in a solid, forces between
  the particles hold them together.

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Thermal expansion

• Since this phenomenon occurs in bridges,
  expansion joints allow bridges to expand in warm
  weather without cracking.

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• Can you imagine the effect that thermal expansion
  and contraction might have on our roads?

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Heat and Phases of Matter

• Heat affects the phases of matter. View this
  video clip to see how.

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Introduction

• There are two types of properties of matter, they
  are physical properties and chemical properties.
  
• There are also two types of changes in matter
  they are physical changes and chemical changes.
• Lets talk about physical properties first.

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Physical Properties

• A physical property is any characteristic of a
  material that one can observe easily without
  changing the substances that make up the
  material.
• Every substance has physical properties that
  distinguish it from other substances.

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Physical Properties

• Physical property examples
• shape
• Size
• Color
• Smell
• Temperature
• Volume
• Density
• melting point
• boiling point
• state of matter.

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Physical Changes

• A change in physical properties is called a
  physical change.
• Physical changes do not alter the identity of a
  substance.
• Pounding, pulling, cutting, dissolving, melting,
  or boiling do not produce a new substance with
  new properties, so they are all physical changes.

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Physical Change Example

• For example if you take a piece of paper and tear
  it into pieces you still have paper. It may be
  smaller, but its still paper.
• You could dye the paper and make it another
  color, but its still paper.
• You have only changed it physically.

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Physical Changes

• When trying to identify a physical change, it is
  important to know that physical changes can be
  reversed.
• For example
• Pieces of paper can be reformed into a new whole
  sheet.
• Ice can be melted, or boiled and then refrozen.

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Physical Changes of Water

• Freezing-liquid to a solid this change requires
  cooling
• Melting-solid to a liquid this change is speeded
  up by heating.
• Condensation-gases change to a liquid this
  change requires cooling.
• Vaporization/Evaporation-liquid changes to gas
  this change is speeded up by heating.
• Sublimation-gas changes to a solid or a solid
  changes to a gas without passing through the
  liquid state (e.g., dry ice, solid to gas)

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What Do You Think?

• Can you name this physical change of water?
• Heres a hint The water is changing from the
  gas to the liquid phase.

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What Do You Think?

• Can you name this physical change of water?
• Heres a hint The water is changing from the
  liquid to the gas phase.

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Review Video

• That was a lot of information. Lets review
  physical properties and physical changes with a
  look at this video clip on states of matter. (18
  min)

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Chemical Properties/Changes

• Substances can change their identities, for
  example, fireworks explode,

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Chemical Properties/Changes

• matches burn

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Chemical Properties/Changes

• Food cooks

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Chemical Properties/Changes

• And iron rusts

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Chemical Properties/Changes

• Burned toast, burned soup, and burned steak all
  smell burned. The smell is different from the
  smell of bread, soup, or steak.
• The odor is a clue that a new substance has been
  produced.

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Chemical Property

• A chemical property is a characteristic of a
  substance that indicates if it can undergo a
  certain chemical change.
• Click the picture for a video clip about chemical
  properties.

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Chemical Change

• A change of one substance in a material to a
  different substance is a chemical change.
• In some chemical changes a rapid production of
  energy, such as the production of heat, light,
  sound or gas bubbles occur. These things
  indicate that a chemical change has occurred.
• Burning and rusting are chemical changes because
  different substances are produced.

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Chemical Change

• A baked cake no longer resembles its ingredients
  of flour, eggs, butter, and sugar, because the
  reactants have undergone a chemical change.
• A chemical reaction is simply breaking substances
  (reactants) apart and making new ones (products)
  from the pieces.

product
reactants
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Chemical Changes

• When trying to identify a chemical change, it is
  important to know that chemical changes can NOT
  be reversed.
• For example
• A cake can not be broken down into eggs, sugar,
  flour, and butter.
• You can not un burn a piece of wood.

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Chemical Reactions

• Those ingredients have been changed by a chemical
  reaction.
• A chemical reaction is simply breaking substances
  (reactants) apart and making new substances
  (products) from the pieces.

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Chemical Reactions

• Whenever a chemical reaction takes place, new
  substances, the products, are made.
• These have very different properties from the
  original starting materials, the reactants.
• reactant reactant product

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Chemical Reactions

• This process involves the rearrangement of atoms
  and molecules, and the making and breaking of
  chemical bonds.

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Closed System

• The mass remains constant, because a chemical
  reaction is a closed system and no matter is
  lost.
• Closed system a system in which the total mass
  of each element in the system remains constant
  before as well as after any kind of chemical or
  physical change.
• No matter is ever created or destroyed during
  the change.

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Chemical Changes

• Heres a video clip that may explain chemical
  changes more clearly.

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Physical Chemical Changes

• Click the links to hear a science guys song on
• Physical Changes
• Chemical Changes