Transcript Chemistry Notes

Chemistry
Notes
What is chemistry?
Study
of matter and its
properties
Why study chemistry?
 Used
in career fields like doctor,
nurse, pharmacist, engineer, rocket
scientist, etc
 Can help you stay healthier – helps
explain reactions in your body and
certain diseases and their
treatments
Matter’ definition
It
has to have 2 things
Has to have mass and
volume
How to describe matter?
 Physical
Properties - properties you can
test for or sense without changing the
substance
 Examples:
density
color
taste
pH
magnetism
boiling point
melting point
odor
Chemical properties

Chemical properties – property in which you
test how it reacts with another substance, and
the substance being tested is changed

Reaction with baking soda
Flammability
Decompose with heat


State of Matter and Their
Properties
All
matter can exist as
a gas, solid, or liquid at
the proper
temperature and
pressure
Solid

Particles are close to one another and
don’t move
Fixed shape
Doesn’t fill container necessarily
High density
Not very compressible

Examples: steel, copper, plastic, ice

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
Gases
 Particles
are far apart and moving fast
 Always fills container
 Takes shape of container
 Least density
 Compressible
Examples: air, natural gas, water vapor
Liquid
 Particles
can move past each other
 Can fill a container
 Takes shape of a container
 Medium density
 Slightly compressible
Examples: liquid water, milk
Two major classifications
Pure
substance
Mixture
Two kinds of pure substances

Element

Definition – pure substance that can’t be broken down
into simpler substances by chemical or physical means

#’s – approximately 118

The substances on the periodic table

Examples: gold, iron, hydrogen, oxygen
Compound

Definition – pure substance made up of two or
more different elements chemically
combined

#’s – millions

Examples: salt, water, sugar
Mixture


Mixture – two or more pure substances physically
combined
Gaseous mixtures – like air

Solid mixtures – like alloys such as brass
and stainless steel

Liquid mixtures – milk, salt water

Mixtures with more than one phase
Carbonated beverages
Separating or purifying matter

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
Mixtures – can be separated by physical
means
Separate a mixture of any two pure liquids
Distillation
Separate the water in salt water from the salts
Boil off the water and salts will remain
Separate a mixture of gases
Cool them – they will condense at
different temperatures
Compounds
Can only be separated by chemical means
 Decomposition
– Heat to high temperature:
Ex. copper oxide ore from the earth – drive off
the oxygen by heating to a high temperature
Electrolysis
Pure water can be separated into hydrogen
and oxygen gases by using an electric current

Elements
Can’t
be purified any further or
broken apart by chemical or
physical means
Chemical Changes

Definition – change in which a substance changes
its chemical identity
Examples
Burning propane
Reaction between vinegar and baking soda

Also called a chemical reaction
Physical changes

Definition – change in which a substance changes
its physical properties without changing its identity.
Examples
Cutting wood
Tearing up a piece of paper
Melting ice
Boiling water