Chemistry: The Study of Matter

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Chemistry The Study of Matter
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What is Chemistry?

• The study of the matter, its composition,
  properties, and the changes it undergoes.
• A natural science.
• a language with its own vocabulary.
• a way of thinking.

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Review of matter

• Matter anything that takes up space (volume)
  and has a mass.
• Physical Properties like different densities,
  melting points, boiling points, freezing points,
  color or smells

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• Chemical Properties A good example of chemical
  properties is the way elements combine with each
  other in reactions

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Review of states of matter
Definite Volume?
Definite Shape?
Temperature increase
Compressible?
Small Expansion
Solid
YES
YES
NO
Small Expansion
Liquid
NO
NO
YES
Large Expansion
Gas
NO
NO
YES
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Liquid
Gas
Solid
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Kinds of Change

• physical change no new substance is formed,
  properties such as size, shape, colour or state
  may change (eg. Boiling water) The reverse is
  possible
• chemical change new substances (with new
  properties) are formed from 2 or more different
  elements. (eg. Rusting of iron) The reverse is
  not possible

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Properties

• Words that describe matter (adjectives)
• Physical Properties- a property that can be
  observed and measured without changing the
  composition of the substance.
• Chemical Properties- a property that can only be
  observed by changing the composition of the
  substance.

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Glossary

• Pure substance contains one type of particle.
  Ex Elements and compounds
• Mixture contains two or more types of particles
  intermingling, no chemical bonding. Types are
  homogeneous and heterogeneous.

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Compounds

• Composed of two or more different atoms
• Can be broken down by chemical methods and each
  part will have different properties
• Examples
• water (H2O), 2 atoms of hydrogen, I atom of
  oxygen)
• salt (NaCl), 1 atom of sodium, 1 atom of chlorine

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Elements

• An element is a substance made up of only one
  kind of atom
• The periodic table arranges elements according to
  their properties

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Compound or Mixture
Compound
Mixture
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Which is it?
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Heterogeneous

• 2 or more parts can be seen
• Different kinds of particles stay together.
• Mechanical mixing
• Ex sand and salt, blood, milk

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Homogeneous

• Appear to be one substance
• Particles are intermingled
• May be solutions (something dissolved)
• Ex air, salt water

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Solutions

• Homogeneous mixture with molecules mixed
  uniformly
• Solutions occur between any state of matter.
• Solid in liquid- Kool-aid
• Liquid in liquid- antifreeze
• Gas in a liquid carbonated beverages
• Gas in gas- air
• Solid in solid - brass
• Liquid in gas- water vapor

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Solutions

• Like all mixtures, the components keep their own
  properties.
• Components can be separated by physical means

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Chemical symbols

• There are 112 elements
• Each has a 1 or two letter symbol
• First letter always capitalized second never
• Dont need to memorize
• Some from Latin or other languages

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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
• NEW PROPERTIES
• Not easily reversed

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Indications of a chemical reaction

• Energy absorbed or released
• Color change
• Gas produced
• Precipitate- solid that separates from solution
• Not easily reversed
• ALWAYS THERE IS A NEW SUBSTANCE!

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Conservation of Mass

• Mass can not be created or destroyed in ordinary
  (not nuclear) changes.
• All the mass can be accounted for.

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What about nuclear?

• E mc2
• energy mass x (speed of light)2
• speed of light 3 x 108
• A little mass can make a lot of energy
• Law of Conservation of Mass - Energy the total of
  the mass and energy remains the same in any change

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Energy

• The ability to do work.
• Work - cause a change or move an object.
• Many types- all can be changed into the other.

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Types of energy

• Potential- stored energy
• Kinetic Energy- energy something has because its
  moving
• Heat- the energy that moves because of a
  temperature difference.
• Chemical energy- energy released or absorbed in a
  chemical change.
• Electrical energy - energy of moving charges

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Types of Energy

• Radiant Energy- energy that can travel through
  empty space (light, UV, infrared, radio)
• All types of energy can be converted into others.
• If you trace the source far enough back, you will
  end up at nuclear energy.

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Conservation of Energy

• Energy can be neither created or destroyed in
  ordinary changes (not nuclear), it can only
  change form.
• Its not just a good idea, its the law.

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Assigned reading

• Page 6-8 and 10-16
• Be able to define or explain the following
  terms/concepts
• Types of knowledge
• Pure/applied science
• Scientific method
• Rules of experimentation
• Laws, theories and models