[CHEM 1122] - Midterm Exam Guide - Ultimate 54 pages long Study Guide!

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CHEM 1122
MIDTERM EXAM
STUDY GUIDE
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Chapter 3- Matter and Energy
MATTER
anything that occupies space and has mass
composed of atoms (submicroscopic particles that are the fundamental building blocks
of matter)
atoms are bonded together to form molecules (two or more atoms joined to one another
in specific geometric arrangements)
CLASSIFYING MATTER ACCORDING TO ITS STATE: SOLID, LIQUID, AND GAS
states of matter: solid, liquid, gas
solid:
atoms and molecules are packed close to each other in fixed locations
fixed volume and rigid shape
crystalline - solid matter may be this, its atoms and molecules arrange in
geometric patterns with long-range, repeating order
atoms or molecules occupy specific positions to create a well-ordered,
three-dimensional structure
ex: salt
amorphous - atoms or molecules do not have long-range order
ex: glass, rubber, and plastic
liquid:
atoms or molecules are close to each other (about as close as molecules in a
solid)
free to move around and by each other
fixed volume because their atoms or molecules are in close contact
liquids assume the shape of their container because the atoms or molecules are
free to move relative to one another
gas:
atoms or molecules are separated by large distances and are free to move
relative to one another
compressible - because the atoms or molecules that compose gases are not in
contact with one another
CLASSIFYING MATTER ACCORDING TO ITS COMPOSITION: ELEMENTS, COMPOUNDS,
AND MIXTURES
we can classify matter according to its composition
pure substance: composed of only one atom or molecule (helium and water)
element: a substance that cannot be broken down into simpler substances
(periodic table)
compound: a substance composed of two or more elements in fixed definite
proportions (more common, water)
mixture: composed of two or more different types of atoms or molecules combined in
variable proportions (air, nitrogen and oxygen gas)
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heterogeneous mixture: composition varies from one region to another
homogeneous mixture: composition is the same throughout
DIFFERENCES IN MATTER: PHYSICAL AND CHEMICAL PROPERTIES
properties: characteristics that distinguish one substance from another
physical property: one that a substance displays without changing its composition
odor of gas (does not change its composition)
boiling point of water (water molecules are the same)
odor taste, color, appearance, melting point, boiling point, density
chemical property: one that a substance displays one through changing its composition
flammability of gas (change composition when it burns)
iron rusting (iron to iron oxide)
corrosiveness, flammability, acidity, toxicity
CHANGES IN MATTER: PHYSICAL AND CHEMICAL CHANGES
physical change: matter changes its appearance but not its composition
ice melts, glass shatters
looks different but same composition
changes in state (melting or boiling)
changes that involve merely appearance (cutting or crushing)
chemical change: matter does change its composition
copper turns green upon continued exposure to air because it reacts with gases
in air to form new compounds
chemical reaction: what happens when matter undergoes a chemical change
reactants: substances present before the chemical change
products: substances present before the chemical change
atoms
physical: atoms that compose the matter do not change their fundamental
associations, even though the matter may change its appearance
chemical: atoms do change their fundamental associations, resulting in matter
with a new identity
PHYSICAL : different form of the same substance
CHEMICAL: completely new substance
SEPARATING MIXTURES THROUGH PHYSICAL CHANGES
decanting - carefully pouring off (separate oil and water)
distillation - to separate mixtures of miscible liquids
heat the mixture to boil off the more volatile (more easily vaporized)
liquid
filtration - if a mixture is composed of a solid and a liquid
pour the mixture through filter paper usually held in a funnel
CONSERVATION OF MASS: THERE IS NO NEW MATTER
matter and energy are the two major components in our universe
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