chemistry notes. what is chemistry? study of matter and its properties
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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’ definitionIt 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 tastepH magnetism boiling pointmelting 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 shapeDoesn’t fill container necessarilyHigh densityNot very compressible
Examples: steel, copper, plastic, ice
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
Two major classifications
Pure substanceMixture
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
Mixtures – can be separated by physical means
Separate a mixture of any two pure liquids
Distillation Separate the water in salt water from the
saltsBoil off the water and salts will remain
Separate a mixture of gasesCool 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 propaneReaction 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 woodTearing up a piece of paperMelting iceBoiling water