Grade 7
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Matter is anything that has mass and takes up
space. Mass is the amount of matter in an
object.
A Solid is matter that has a definite shape and
volume
A liquid is matter that does not have a
definite shape, but has a definite volume
A gas is matter that does not have a definite
shape or volume
(but you knew that already didn’t you  )
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All matter can also be grouped into two basic
categories: pure substances, and mixtures
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A Pure Substance is made up of only one type
of matter.
Sugar, distilled water, and copper wire are all
types of pure substances.
For example, all the parts in a packet of sugar
are the same.
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Pure substances appear homogeneous. This
means that every part of that substance has
the same composition as every other part.
When you look at a container of salt, or
distilled water, every part of that substance
looks the same.
The prefix “homo” comes from the Greek
work “homos” which means “same”.
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A mixture is made up of two or more
different substances.
For example, a pizza is a mixture of different types
of edible ingredients placed on flat dough. Mmm.
Each substance in a mixture keeps its
particular properties even though they may
be hard to see.
For example, you can not always see the sugar that is in
a soft drink – even if you can taste it.
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Mixtures can also be grouped into two basic
categories: mechanical mixtures and
solutions.
When you look at mechanical mixtures closely
they do not have the same appearance
throughout. They are heterogeneous. You can
see the differences with the naked eye.
The prefix “hetero” comes from the Greek
work “heteros” which means “different”
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Mechanical Mixtures are also called
heterogeneous mixtures.
This means they are made up of many
different substances, each with different
appearances and properties.
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Solutions have the same appearance
throughout but are made of two or more
substances.
When you mix one substance in another to
form a solution, you dissolve one substance
in the other.
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All solutions are homogeneous mixtures
because they look the same throughout, even
through they are made up of different
solutions.
For example, when you dissolve sugar in tea,
the tea looks the same throughout.
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Categorize each item as a pure substance or
a mixture on the chart in your booklet.
chocolate pudding
unfiltered tap water
Gatorade
gold necklace
Bleach
a diamond
helium gas
pepper
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The Particle Theory of Matter is a theory that
describes matter. It explains the behaviour of
solids, liquids and gasses.
Copy the 6 postulates of the theory into your
booklet form page 200 in your textbook.
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All matter is made of particles. The particles
in matter are in constant motion. They move
and vibrate constantly.
Particles move because they have kinetic
energy. Kinetic energy is the energy of
movement.
Temperature is the average kinetic energy of
the particles in a substance. It measures how
hot a substance is.
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Heat is the energy that transfers from a
substance at a higher temperature to one at a
lower temperature.
Temperature affects the speed at which
particles move.
the higher the temperature: the more the
movement of energy in the particle.
the lower the temperature: the less the movement
of energy in the particle.
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There are spaces between particles. There is
also a force of action between particles.
These forces have differing strengths in
solids, liquids and gasses.
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Solutions can occur as solids, liquids or
gasses.
Solid solutions are called alloys.
Liquid and gaseous solutions are simply
called solutions.
This brass door knocker is a mixture of
copper and zinc.
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Solutions consist of solutes and solvents.
A solute is the substance that dissolves. A
solvent is the substance into which the solution
dissolves.
For example, in seawater, salt and other
substances (solutes) dissolve in water (solvent)
Water is often referred to as the Universal
Solvent, because many different solids, liquids
and gasses dissolve into it to form solutions.
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Solubility refers to the ability of a solute to
form a solution when added to a certain
solvent.
To form a solution the solute must be
attracted to the solvent particles, which
allows the particles to spread evenly
throughout the solution.
For example, salt dissolves in water because
the salt particles are attracted to the water
particles.
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Salt water does not dissolve in olive oil
because the salt particles are not attracted to
the oil particles.
When a substance does not dissolve in a
solvent, that substance is insoluble in that
solvent.
A solution does not form when one of the
substances is insoluble to another.
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A concentrated solution is a solute that has a
large amount of dissolved solute and very
little solvent.
A diluted solution has very little solute
dissolved in the solvent.
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The concentration of a solution is the amount
of solute dissolved in a specific amount of
solvent.
For example, if 5g of salt are dissolved in
500ml of water, the concentration of the
solution is 5g/500ml
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In all solutions, there is a maximum
amount of solute that can be dissolved in a
given solvent at a given temperature – this
is called saturation
A saturated solution is
one that has been
formed from the
maximum amount of
solute for a given amount
of solvent at a certain
temperature.
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Every solution has a saturation point, which
means no more solute can be dissolved into a
fixed volume of solvent at that temperature.
That is why there is sometimes extra
undissolved delicious Kool Aid powder at the
bottom of your class.
Yummm.
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If more solute can be dissolved in a solvent at
a given temperature, then the solution is
unsaturated. You can dissolve more solute in
an unsaturated solution.
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The particle theory of matter explains how
solutes dissolve in solvents
The rate of dissolving is affected by stirring,
temperature and particle size
Stirring a solution increases
the rate in which a solute
dissolves in a solvent
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Temperature affects the speed at which
particles move. When particles move faster,
more solvents and solute particles will bump
into each other. This will quickly spread the
solute particles throughout the solvent.
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Large particles take longer to dissolve than
smaller particles of the same substance.
For example, sugar cubes dissolve more
slowly than granular sugar.
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Last topic – Separating solutions and mixtures! Aren’t
Pure Substances and Mixtures fun! ....all these
delicious sugary pictures are making me hungry...
The components of a solution have very
similar properties and characteristics, which
make them difficult to separate.
The most common strategy involves making
the solvent or solute change state so that it
can be removed from the solution.
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In paper chromatography a highly concentrated
solution is placed on a single spot and is absorbed by
the paper. The paper is dipped in a solvent so that
the spot is above the solvent. The solvent moves
through the paper because the solvent particles are
attracted to the paper particles and to one another.
Different compounds travel different distances from
the starting point and become separated.
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When you heat up an object, eventually all of the
water particles leave the solution, leaving the
solute particles behind.
Maple syrup is made by boiling maple sap. This
causes the water in maple sap to evaporate,
which leaves behind a concentrated solution of
maple syrup.
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Distillation enables you to retain both the
solute and the solvent from a solution.
During the distillation process, the solution is
boiled, which vaporizes the solvent. The
solute remains in the original container, but
the solvent condenses and is collected.
This process removes salt
from water so it can be drank.
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Generally speaking, separating mechanical
mixtures is easier, because the components
of the mechanical mixture are usually quite
different from each other.
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Filtration is the mechanical process of
separating solids from liquids or gases using
a porous article or mass, such as paper or
sand.
When the mixture is poured into the filter, the
solid parts are trapped in the filter, and the
liquid passes through.
Filtrations is used to
separate solids from liquids
or gases.
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Sorting is a technique that involves separating
substances on the basis of appearance (e.g. Size,
colour, composition)
We should practice this technique to ensure our
garbage is put where it belongs!
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Sifting is a means of separating solids by
component size. It involves shaking a solid
material while it passes through a screen or
mesh.
Componenets of the solid materials that are
small enough to pass through do, separating
them from larger components.
Sifting is used to separate solids from solids.
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Some metals are magnetic because their
component particles are attracted to the
particles within magnets
Iron, steel, and nickel are highly attracted to
magnets, whereas most other substances are
not. Therefore, you can use a magnet to
separate magnetic materials from ones which
are not.