Transcript chapt1intro to chem

Chemistry: The Study of
Matter
What is Chemistry?
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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.
Review of matter:
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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
Review of states of matter
Definite Definite Temperature
Volume? Shape? increase
Solid
Liquid
Gas
YES
YES
NO
Compressible?
YES
Small
Expansion
NO
NO
Small
Expansion
NO
NO
Large
Expansion
YES
Condense
Freeze
Evaporate
Melt
Solid
Liquid
Gas
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
Properties
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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.
Glossary:
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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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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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An element is a
substance made up of
only one kind of atom
The periodic table
arranges elements
according to their
properties
Compound or Mixture
Compound
One kind of matterMolecule or atom
Mixture
More than one kind of
matter- different molecules
or atoms
Made during a
Made through a
chemical change
physical change
Definite and uniform
composition
Variable in composition
Which is it?
Mixture
Element
Compound
Heterogeneous
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2 or more parts
can be seen
Different kinds of
particles stay
together.
Mechanical
mixing
Ex: sand and
salt, blood, milk
Homogeneous
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Appear to be one
substance
Particles are
intermingled
May be solutions
(something dissolved)
Ex: air, salt water
Solutions
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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
Solutions
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Like all mixtures, the components keep
their own properties.
Components can be separated by physical
means
Chemical symbols
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There are 112 elements
Each has a 1 or two letter symbol
First letter always capitalized second never
Don’t need to memorize
Some from Latin or other languages
Chemical Reactions
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When one or more substances are
changed into new substances.
Reactants- stuff you start with
Products- What you make
NEW PROPERTIES
Not easily reversed
Indications of a chemical
reaction
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Energy absorbed or released
Color change
Gas produced
Precipitate- solid that separates from
solution
Not easily reversed
ALWAYS THERE IS A NEW SUBSTANCE!
Conservation of Mass
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Mass can not be created or destroyed in
ordinary (not nuclear) changes.
All the mass can be accounted for.
What about nuclear?
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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
Energy
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The ability to do work.
Work - cause a change or move an object.
Many types- all can be changed into the
other.
Types of energy
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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
Types of Energy
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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.
Conservation of Energy
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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.
Assigned reading:
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Page 6-8 and 10-16
Be able to define or explain the following
terms/concepts
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Types of knowledge
Pure/applied science
Scientific method
Rules of experimentation
Laws, theories and models