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Module 5
Review
States of Matter
05.01 Physical Changes
• Physical properties can be observed, measured, or changed
without changing the identity or make up of a substance.
These physical properties can help us distinguish one type of
matter from another.
• Physical properties include: (Check out lesson 4.08)
– Shape
– Size
– Melting Point
– Density
• A physical change is any change in the property of matter
that does not change the make up of the substance.
05.01 Physical Changes continue..
• In a physical change, the chemical make up of a substance
does not change. The only thing that changes is a physical
property such as:
– Color
– Shape
– Phase (solid, liquid, or gas)
– Size
• Examples:
Cutting, ripping,
breaking, phase
change are all
physical changes
5.02 States of Matter
• The three main states of matter are:
– Solid
– Liquid
– Gas
Melting and boiling are
physical changes
between different states
of matter, or phases, of
the same substance.
A sample of matter
will have the same
chemical composition
whether it is a solid,
liquid, or gas. The
difference between
the states of matter is
the behavior and
arrangement of the
atoms or compounds
5.02 States of Matter
A change in the state of matter, also known as a phase
change, is an example of a physical change.
5.03 Chemical Changes
• A chemical change is a change one or more substances undergo
when they become new or different substances.
• Another name for a chemical change is a chemical reaction.
• Examples:
The light, sound, heat, bubbling, fizzing, odor, production of gases, and
color are all signs that a chemical change is occurring.
• When a chemical change or reaction occurs:
– The substances at the end of the reaction have different properties than
the original substances.
– The chemical bonds holding atoms together as compounds are broken.
– New chemical bonds are formed, resulting in new chemical compounds.
5.03 Chemical Changes
• Chemical changes occur on the molecular level, by
breaking the bonds in chemical compounds and then
forming new compounds. The amount of each type of atom
is still the same at the end of the reaction, but their
arrangement is different when the new bonds are formed.
5.04 Temperature and Chemical Change
• Every reaction includes heat! Chemical and physical changes are
accompanied by energy changes. Energy, usually in the form of heat, may
either be released or absorbed when a change in matter occurs.
• Scientists use a thermometer to determine if a change was endothermic or
exothermic.
If the thermometer shows an
increase in temperature, the
reaction gave off heat energy. This
means the reaction was exothermic.
If the thermometer shows a decrease
in temperature, the reaction took in
heat from the surroundings. This
means the reaction was
endothermic.
Endothermic Vs. Exothermic
In a phase change, if the particles of matter are being
pulled farther apart from each other, that will require energy.
• Melting and boiling are endothermic processes; they require the addition
of heat in order to occur. If the particles are becoming more condensed
or coming closer together, energy will be given off.
• Condensation and freezing are exothermic processes that give off heat
as they occur.
5.04 Temperature and Chemical Change
5.05 Physical vs. Chemical Changes
Physical Changes
Chemical Changes
changes in form and
shape only
changes in the nature of the
matter
the form or the
appearance of the matter
changes;
Bonds are broken and new
bonds are formed; New
substance is formed with
different properties
composition of the matter
does not change during a
physical change
the composition of the
matter changes.
Reversible
Not reversible
Example: Ripping paper
Example: Burning paper
5.06 Laws of Conservation of Mass and Energy
The law of conservation of mass says that matter
cannot be created or destroyed by ordinary
chemical or physical changes.
This means:
• The mass will be the same before and after the chemical or physical
change
• There are the same number of each type of atom before and after the
change
• The total mass of all components of a chemical reaction or physical
change can be measured before and after the change to demonstrate
that the mass is constant.
5.06 Laws of Conservation of Mass and Energy
The law of conservation of Energy says energy can
be converted from one form to another, but it
cannot be created or destroyed in ordinary
chemical or physical changes.
This means:
• The energy will be the same before and after the chemical or
physical change
• Energy can be more challenging for scientists to keep track of
during a chemical reaction than mass. Mass is able to be
measured on a balance before and after the change, but
scientists must use more advanced techniques to measure the
energy in a system.
5.06 Laws of Conservation of Mass and Energy
Examples
Plants convert energy from the sun to
chemical energy that we use as food
in a process known as photosynthesis.
Chemical energy in compounds like
wood, coal, and natural gas is converted
to heat energy as burning occurs.
The energy of wind is converted to
mechanical and electrical energy as
the wind turbine is turned.
05.07 Law of Conservation of Mass Activity
In chemical reactions, under ideal conditions, the total mass of
reactants and the total mass of products are equal. This is known
as the Law of Conservation of Mass.
Module 5 Review
• Be sure to review:
• The characteristics of chemical and physical changes.
• The states of matter.
• Endothermic and exothermic reactions.
• The law of conservation of mass and energy.
• The law of conservation of mass activity.
Module 5 Review
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