Chapter 2 Matter and Change

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Chapter 2Matter and Change

• Charles Page High School
• Dr. Stephen L. Cotton

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Section 2.1Matter

• OBJECTIVES
• Identify the characteristics of matter and
  substances.

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Section 2.1Matter

• OBJECTIVES
• Differentiate among the three states of matter.

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Section 2.1Matter

• OBJECTIVES
• Define physical property, and list several common
  physical properties of substances.

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What is Matter?

• Matter is anything that takes up space and has
  mass.
• Mass- amount of material or stuff in an object
• Weight is due to gravity, and changes from
  location to location mass is always constant.

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Types of Matter

• Substance- a particular kind of matter - pure is
  uniform (all the same) and has a definite
  composition (examples are elements compounds)
• water gold lemonade?
• Mixture- more than one kind of matter has a
  variable composition

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Properties

• Words that describe matter (adjectives)
• Physical Properties- a property that can be
  observed and measured without changing the
  composition.
• Examples- color, hardness, m.p., b.p.
• Chemical Properties- a property that can only be
  observed by changing the composition of the
  material.

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States of matter

• Solid- matter that can not flow (definite shape)
  and has definite volume.
• Liquid- definite volume but takes the shape of
  its container (flows).
• Gas- a substance without definite volume or shape
  and can flow.
• Vapor- a substance that is currently a gas, but
  normally is a liquid or solid at room
  temperature. (water vapor?)

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States of Matter
Definite Volume?
Definite Shape?
Temp. increase
Com-pressible?
Small Expans.
Solid
YES
YES
NO
Small Expans.
Liquid
NO
NO
YES
Large Expans.
Gas
NO
NO
YES
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Liquid
Gas
Solid
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Physical Changes

• A change that changes appearances, without
  changing the composition.
• Ex. Boil, melt, cut, bend, split, crack
• Boiled water is still water.
• Chemical changes - a change where a new form of
  matter is formed.
• Ex. Rust, burn, decompose, ferment

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Section 2.2Mixtures

• OBJECTIVES
• Categorize a sample of matter as a substance or a
  mixture.

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Section 2.2Mixtures

• OBJECTIVES
• Distinguish between homogeneous and heterogeneous
  samples of matter.

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Mixtures

• Physical blend of at least two substances
  variable composition
• Heterogeneous- mixture is not uniform in
  composition
• Chocolate chip cookie, gravel, soil.
• Homogeneous- same composition throughout called
  solutions
• Kool-aid, air, salt water
• Every part keeps its own properties.

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Solutions

• Homogeneous mixture
• Mixed molecule by molecule
• Can occur between any state of matter
• Table 2.3, page 33
• gas in gas liquid in gas gas in liquid solid
  in liquid solid in solid (alloys), etc.

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Solutions

• Like all mixtures, they keep the properties of
  the components.
• Some can be separated easily by physical means
  rocks and marbles, iron filings and sulfur
• Other methods distillation- takes advantage of
  different boiling points

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Section 2.3Elements and Compounds

• OBJECTIVES
• Explain the differences between an element and a
  compound.

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Section 2.3Elements and Compounds

• OBJECTIVES
• Identify the chemical symbols of common elements,
  and name common elements given their symbols.

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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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Compound or Mixture
Compound
Mixture
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Which is it?
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Chemical Symbols Formulas

• Currently, there are 115 elements
• Each has a 1 or two letter symbol
• First letter always capitalized the second
  never chemical shorthand
• Dont need to memorize all of them know Table
  A.3 inside back cover
• Some from Latin or other languages note Table
  2.4, page 40

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Section 2.4Chemical Reactions

• OBJECTIVES
• Differentiate between physical and chemical
  changes in matter.

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Section 2.4Chemical Reactions

• OBJECTIVES
• Apply the Law of Conservation of Mass.

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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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Law of Conservation of Mass

• Mass can not be created or destroyed in ordinary
  (not nuclear) chemical reactions or physical
  change
• All the mass can be accounted for.
• Burning of wood results in products that appear
  to have less mass as ash where is the rest?