Words to Study for Chem. Test
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Mass
Weight
Matter
Physical Properties
Chemical Properties
Characteristic Properties
Physical Changes
Chemical Changes
Signs of Chem. Change
States of Matter
Atoms
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Solid
Liquid
Gas/Gas Laws
Change of State
Melting/Melting Point
Boiling/Boiling Point
Freezing/Freezing Point
Evaporation
Condensation
Sublimation
Endo/Exothermic
Words to Study for Chem. Test
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Solution
Solubility
Suspensions
Colloids
Pure Substance
Element
Compound
Mixture
Homogeneous Mixture
Heterogeneous Mixture
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Chemical Formulas
Chemical Equations
Reactants
Products
Subscripts
Coefficients
Law of Conservation of Mass
Decomposition Reaction
Replacement Reaction
Synthesis Reaction
Chemical Formulas
• A combination of chemical symbols and
numbers to represent a substance
• Examples
– H20: Water
– CO2: Carbon Dioxide
– NaCl: Salt
– C6H1206: Sugar
Chemical Equations
• A representation of a chemical reaction that
uses symbols to show the relationship
between the reactants and the products
• Examples
C + O2  CO2
2H2 + O2  2H2O
Reactants
• A substance or molecule that participates in a
chemical reaction
• Examples
C + O2  CO2
Reactants
2H2 + O2  2H2O
Reactants
Products
• A substance that forms in a chemical reaction
• Examples
C + O2  CO2
Product
Zn + 2HCl  ZnCl2 + H2
Product
Subscripts
• A number written below and to the right of a
chemical symbol in a formula
• Tells how many atoms of that element are
present
• Examples
– CO2
– H20
– C6H12O6
Coefficients
• A number that is placed in front of a chemical
symbol or formula
• Tells how many molecules of that substance
are present
• Keeps reaction balanced
• Example
2H2 + O2  2H2O
Law of Conservation of Mass
• Mass is neither created nor destroyed in
ordinary chemical and physical changes
• Must start and end with the same amount
• Example
Log +
30 kg
Fire
1 kg

Ashes
28 kg
+
Smoke
3 kg
Decomposition Reaction
• A reaction in which a single compound breaks
down to form two or more simpler
substances
• Example
H2CO3  H2O + CO2
Replacement Reaction
• A reaction in which one element takes the
place of another element in a compound
• Example
Zn + 2HCl  ZnCl2 + H2
Synthesis Reaction
• A reaction in which two or more substances
combine to form a new compound
• Example
2Na + Cl2  2NaCl
Solution
• A homogeneous mixture of 2 or more
substances evenly dispersed throughout a
single phase
• Looks like one thing
• Usually when 1 substance is dissolved in
another, but not always
– Examples: Lemonade, Air, Bronze, Gatorade
Solubility
• Ability of 1 substance to dissolve in another
• To dissolve more quickly: Crush it, Stir it, Heat
it
• Solute – the substance that is dissolved
• Solvent – what substance is being dissolved
in
– Example: Sugar dissolves in water
Suspensions
• A mixture in which particles of a material are
more or less evenly dispersed throughout a
liquid or gas
• When you shake it, it looks like one thing, but
if you leave it setting, particles will settle to
bottom
– Example: Snow Globe
Colloids
• Mixture consisting of tiny particles that are
intermediate in size between those in
solutions and those in suspensions
• Particles aren’t so small that they completely
dissolve like solutions, but aren’t so big they
settle
– These particles can scatter light
– Example: Milk, Mayo, Deodorant
Homogeneous Mixture
• Looks like or appears to be only 1 substance
• Example
– Gatorade
– Lemonade
Heterogeneous Mixture
• Looks like or appears to be more than 1
substance
Pure Substance
• Sample of matter, either a single element or
a single compound, that has a definite
chemical & physical properties
• Made of only 1 type of particle
– Elements or Compounds
• Elements – made of atoms
• Compounds – made of molecules
Element
• A substance that can’t be separated or
broken down into simpler substances by
chemical means
• Pure substance
• Can’t be broken down at all
• Made of one type of atom
• Found listed on Periodic Table
Compound
• Substance made up of atoms of 2 or more different
elements chemically combined with specific mass
ratio
• Can only be separated by chemical changes
• Made only of molecules
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H20: Water
NaCl: Salt
C6H12O6: Sugar
Fe2O3: Rust
• Properties of compound are completely different
from the properties of elements that formed it
Mixture
• Combination of 2 or more substances that are
not chemically combined
• 2 or more things physically in the same place
– Examples: Salad, Cereal, Pizza, Omelette
Change of State
• Change of a substance from one physical
form to another
• Requires adding or removing energy so that
particles can speed up or slow down
Endothermic
• Energy is absorbed by a substance or
substances
Exothermic
• Energy is released from a substance or
substances
Melting
• Change of state when a solid becomes a
liquid
• Particles must speed up
• Add energy/heat
• Endothermic
Melting Point
• Temperature at which a substance melts
• Water: 32°F or 0°C
Freezing
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Change of state from a liquid to a solid
Particles must slow down
Remove energy/heat
Exothermic
Freezing Point
• Temperature at which a substance freezes
• Water: 32°F or 0°C
Evaporation
• Change of a substance from a liquid to a gas
(only on surface)
• Particles (on surface) must speed up
• Add energy/heat
• Endothermic
Boiling
• Change of a liquid to a gas (throughout an
entire liquid)
• Particles (on bottom of liquid) must speed up
• Add energy/heat
• Endothermic
**Won’t happen unless air pressure equals
pressure in bubbles
Boiling Point
• Temperature at which a substance boils
• Water: 212°F or 100°C
• At Sea Level: boiling depends on air pressure
Condensation
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Change of state from a gas to a liquid
Particles must slow down
Remove energy/heat
Exothermic
Sublimation
• Change of state from a solid to a gas
– Example: Dry Ice
• Skips liquid stage
• Add energy/heat
• Endothermic
To Access the BBC Video:
• In Internet Explorer, go to
www.tinyurl.com/christscience7
• Click on Unit 2
• Under Class Files/Links, click on
Behavior of Matter Test Bite (BBC)
• When finished, turn in questions to
your period’s colored drawer 
Atoms
• Smallest unit of an element that maintains
the properties of that element
• Can not be broken down into anything
smaller
• Scientists used to think they couldn’t be split,
but we now know that was incorrect
States of Matter
• The physical forms of matter, which include
solid, liquid, and gas
Solid
• The state of matter in which the volume and
shape of a substance are fixed
• Definite shape
• Definite volume
• Particles are tightly packed
• Particles barely move
– They vibrate in place
Liquid
• The state of matter that has a definite
volume but not a definite shape
• No definite shape
• Definite volume
• Particles move fast enough to separate a little
– Allowing them to change shape
• Particles do not move fast enough to change
volume
Liquid (Continued)
• Viscosity: a liquid’s resistance to flow
– High Viscosity: Slow Flow (Honey)
– Low Viscosity: Fast Flow (Water)
• Surface Tension: force that attracts the
molecules at the surface of a liquid to form
the drop
Gas
• The state of matter that does not have a
definite shape or volume
• No definite shape
• No definite volume
• Particles move so fast that they completely
separate from each other
– Allowing them to change shape and volume
Gas Laws
• If Temperature remains Constant, Hallway
– Volume Increases, Pressure Decreases
– Volume Decreases, Pressure Increases
– Inversely Proportional
• If Pressure remains Constant,  Balloon
– Temperature Increases, Volume Increases
– Temperature Decreases, Volume Decreases
– Directly Proportional
Physical Changes
• A change of matter from one form to another without a
change in chemical properties
• Usually reversible, no change to matter composition
• End with the same thing you started with
• Examples:
– Ripping
– Crushing
– Cutting
– Heating
– Cooling
– Coloring
– All changes of state
Chemical Changes
• A change that occurs when one or more substances change
into entirely new substances with different properties
• Never reversible
• End with something different than you started with
• Examples:
– Soured Milk
– Burning
– Digesting
– Cooking/Baking
– Rotting/Spoiling
– Tarnishing
Signs of a Chemical Change
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Change in color
Change in temperature
Fizzing/Foaming
Sound or light being given off
New smell
New taste
Precipitate – when two liquids are mixed together
and form a solid
Mass
• A measure of the amount of matter in an object
• Mass of an object is the same no matter where it
is located
• Only way to change is to add or take away matter
• Unit/Tool:
– Grams (g)
– Balance
Weight
• A measure of the gravitational force exerted on an
object
• Changes when the force of gravity changes
– Differs on Earth & Mars
• Unit/Tool:
– Newtons (N)
– Spring Scale
Matter
• Anything that has mass and takes up space
• Made up of tiny particles called atoms
– Atoms: smallest particle of matter
Physical Properties
• Can be observed or measured without changing
the matter’s identity
• Adjective – descriptive word
• Examples
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Color
Smell
Size/Shape
Texture/Taste
Temperature
Density
State (Solid, Liquid, Gas)
Chemical Properties
• Substance ability to participate in chemical
reactions
• Hard to observe
• In order to see these you must change the
substance into a new substance
• Examples
– Flammability
– Reactivity
Characteristic Properties
• Chemical or physical property that is always the
same no matter what size the sample is
• Can be physical or chemical
• Most useful type of property
• Examples
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Density
Flammability
Reactivity
Boiling Point, Melting Point, Freezing Point
Color
Smell