Name: ____________________________________
Class: _____________________________________
Science 7
Pure Substances & Mixtures Miss Tse
Tse Science 7 Name: __________________________
1
Unit 2: Topic 1
Matter in Your World
Matter:
Properties:
Mixture:
Mixture Flow Chart
Tse Science 7 Name: __________________________
2
According to our flow chart, there are two categories of mixtures:
1) Heterogeneous (Mechanical) Mixture:
Ex.
2) Homogenous (Solution) Mixture:
Ex.
Tse Science 7 Name: __________________________
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Unit 2: Topic 2
Particle Theory of Matter
Pure Substances:
Ex.
Particle Theory of Matter:
1.
2.
3.
4.
5.
Tse Science 7 Name: __________________________
4
What Makes Materials Dissolve?
____________________________: when a solution
is formed by mixing two or more materials
For example, when we mix sugar into water, the
particles of water can attract a sugar particle more
strongly than the other sugar particles around it.
First, the water particles pull a sugar particle away from the other particles. Then the
motion of the water carries it away. This makes room for more water particles to move in
and attract another sugar particle. This process continues until all of the sugar is
dissolved.
Diagram:
When sugar dissolves in water, we call the water the ______________________ and the
sugar the _______________________.
Solute:
Solvent:
Tse Science 7 Name: __________________________
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Why Do Some Materials Not Dissolve?
Insoluble:
Ex.
Mixing materials together does not always result in a _________________.
Why do they not mix together?
This depends on the attraction between the particles.
For example, grass stains are very hard to get out clothing. That is
because the chlorophyll in the grass are more attracted to each
other than the water particles you are putting on it to wash it out.
You would need to use a different solvent that the chlorophyll is
more attracted to!
Tse Science 7 Name: __________________________
6
Unit 2: Topic 3
Energy Changes
ENERGY:
- Whenever a change occurs, energy is transferred from one object to another
Energy is a property or quality of an object or substance that gives it the ability to
move, do work, or causes change.
Law of Conservation:
Thermal Energy:
- This is also the total kinetic energy of all the particles in a substance
- Thermal energy can be _____________________ and ______________________
For example: The particles in a hot air balloon
BEFORE HEATING AFTER HEATING
Tse Science 7 Name: __________________________
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Two things you must know about energy:
1. Changes happen when there is a difference of energy
Examples:
2. Energy is always transferred in the same direction
- Energy goes from a ________ energy source to something with ________energy
Heating and Cooling
- Heating anything increases the ____________ energy of all it’s particles
BUT
the _____________ energy of the particles (which is the temperature of
the substance) may increase or stay the same, depending on the number of
particles (the amount of material that is being heated)
- Decreasing the temperature of an item means that the object _________________
the material _________________ the thermal energy.
o This means that there is ___________ energy in the material so the
average motion of the particles slows down
For example: an ice cube in a warm drink
The ice cube will absorb the thermal energy as the soda
cools down. Now the soda will have less energy so particle
movement slows.
Tse Science 7 Name: __________________________
8
Unit 2: Topic 4
Expansion and Contraction
As a substance warms up, the particle model of matter states that the particles move faster
and spread apart.
This means that we expect the substance to _______________________ (increase
in volume) as their temperature rises.
As well, we expect that substances will ___________________________
(decrease in volume) as they cool down.
We can check these predictions by using pure substances. A pure substance is:
A pure substance can exist as a ___________________, _____________________, or
_______________.
By testing pure substances, we have learned that substances in a:
- ______________________ State are materials that will keep their shape and size
because solids have a definite shape and cannot be compressed into a smaller
space
- ______________________ State are materials that have a definite size (volume)
but no fixed shape.
o Liquids cannot be compressed
- _______________________ State have no definite shape or volume. They expand
to fill all parts of their container and can be compressed into a small space.
Expansion and Contraction in Liquids
Ex. How a thermometer works
Cold Water Hot Water
Tse Science 7 Name: __________________________
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Unit 2: Topic 5
The Particle Model and Changes of State
Changes of State
Sublimation:
Changes in temperature are signs of changes in particle motion, which means
changes in thermal energy.
Melting and Boiling Points
- The melting and boiling points of a substance are important pieces of information
Melting Point:
Boiling Point:
Substance Melting Point (°C) Boiling Point (°C)
Oxygen -218 -183
Mercury -39 357
Water 0 100
Lead 328 1740
Tse Science 7 Name: __________________________
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What Happens When A Liquid Evaporates?
In a liquid, particles are moving at different speeds.
At the surface of a liquid, the faster moving particles are able to escape into the air. As
the particles leave the liquid, the remaining liquid is cooler than the original liquid.
The slower particles stay in liquid state. If the particles move slower, it means it has
lower energy, meaning lower temperature.
Evaporative Cooling:
REMEMBER: the average speed of the particles does not change because temperature
stays constant during a phase change (ex. Liquid to gas).
The only thing that does change is the arrangement of the particles.
Particles become less organized as their energy increases.
Particles become more organized as their energy decreases.
The total energy of a substance increases or decreases during a phase change. This
happens because the particles are no longer increasing or decreasing their speed, it is the
arrangement of these particles that change.
The average energy of the particles DOES NOT change so the temperature of the
substance stays constant.
Here are some diagrams:
Tse Science 7 Name: __________________________
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Unit 2: Topic 6
Transferring Energy
Energy Source:
There are three ways in which energy can be transferred.
1.
2.
3.
1. Radiation
For example: the sunshine that is powering your calculator is a type of radiation. There is
no physical material that travels from the sun to your calculator.
BUT, even though there is no physical material travelling, there is energy being
transferred.
This is called ____________________________________________ or
_____________________.
It is:
This kind of energy travels through space by the form of ________________. EMR can
travel through empty space, air, glass and many other materials.
There are many different types of EMR such as microwaves, visible light, and X-rays.
Tse Science 7 Name: __________________________
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If the energy source is a warm object like the Sun, it has _________________________.
This energy is transferred as a type of EMR, called infrared radiation.
All radiant energy share several characteristics:
- They behave like waves
- They can be absorbed and reflected by objects
- They travel across empty space at the same very high speed (300 000 km/s)
Reflectors Absorbers
2. Conducting Energy Through Solids (Conduction)
In solids, the particles look like:
Thermal Conduction:
Tse Science 7 Name: __________________________
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Conductors Insulators
When insulators are wrapped around
an object, they slow down the
transfer of thermal energy to or from
the surroundings.
Ex. Ex.
3. Convection
- Thermal energy can be transferred by __________________.
Fluids:
Convection is when:
Why and how are convection currents created?
Tse Science 7 Name: __________________________
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When something is warmed up, the particles move farther apart. Each section of
the warmed materials is left with fewer particles than when it was cold, so that section is
lighter than it used to be, meaning it is less dense.
Cold and dense air sinks down and pushes nearby warm fluid upwards. Then the
cold fluid is warmed up and pushed up as well.
As that warm air rises up and away from the heat, it starts to cool down. When it
cools down, the spaces between the particles contract and makes it become denser. When
it becomes denser, it sinks back down where it gets warmed up again.
The process continues again as a continuous movement.
Transferring Energy
Tse Science 7 Name: __________________________
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Unit 2: Topic 7
Sources of Thermal Energy
Different Types of Energy
1. Chemical Energy
Examples of chemical energy are:
2. Electrical Energy
Examples of electrical energy:
Electricity can be produced at generating stations that burn fossil fuels. Where large dams
cannot exist, fuel-burning generating stations are used to provide electrical energy to
large populations.
- The heated water is a product of these generating stations. This hot water is
released into lakes and rivers that can be dangerous to the organisms living
there.
- Also, the chemicals that released when burning fossil fuels can cause damage
to the environment.
3. Mechanical Forces
Thermal energy can be released due to the impact of physical contact.
Tse Science 7 Name: __________________________
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4. Geothermal Energy
Examples of geothermal energy are:
One technique for using geothermal energy is called HDR (hot, dry rock). Engineers
pump water into rock that has been cracked. The water returns to the Earth’s surface as
steam. This steam is used to generate electricity.
Geothermal energy is clean and is a good alternative to burning fossil fuels since we are
running out of these resources. Also, geothermal energy reduces the wastes that are
produced by mining and burning fossil fuels.
5. Solar Energy
Solar energy is clean and not likely to run out.
Although, one disadvantage of using solar energy is the fact that there are periods of time
where the Sun does not shine.
- Solar energy is not available through the night.
- There is less solar energy available during the winter than summer
a. Passive Solar Heating
b. Active Solar Heating
Tse Science 7 Name: __________________________
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Active solar heating uses complex devices that are called ________________________.
These are usually on the roof of a building and contain water or air. The Sun then heats
the water or air and is then pumped through the building.
6. Wind Energy
Wind energy is a result of solar energy.
As the Sun heats the air, warmer air rises and cools down. The cooler air creates
convection currents. This forms our wind systems.
Wind energy can be harnessed to produce electricity. A turbine does exactly that. The
wind helps rotates an electrical generator that creates electricity.
7. Warm Blooded Organisms - Organisms release energy for their body’s growth and activity. That thermal
energy is transferred to the air and objects around them.
- A composter (decomposer) breaks down food which releases thermal energy
which helps in decomposition
Fossil Fuels
Energy Resource:
Fossil Fuels:
Tse Science 7 Name: __________________________
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There are two major problems with fossil fuels:
1. Society’s use of fossil fuels has increased rapidly over the years.
- As a result, fossil fuels will be very expensive and difficult to obtain
Fossil fuels are considered to be a non-renewable resource. These are:
Renewable resource:
Ex.
2. Another problem is that when fossil fuels are burned, they produce carbon dioxide
gases.
- The amount of carbon dioxide that is being produced ruins natural carbon
dioxide recycling systems such as plants.
- The large amount of carbon dioxide gets stuck in the atmosphere and becomes
a greenhouse gas
Greenhouse gases:
These greenhouse gases contribute to global warming.
Normally, small amounts of carbon dioxide in the atmosphere helps keep the Earth warm
enough to support life. But due to the increased amounts, thermal energy is being trapped
which is warming Earth very quickly.
Due to this warming, lakes and rivers are drying up and icebergs are starting to
melt.
Tse Science 7 Name: __________________________
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Unit 2: Topic 8
Conserving Our Fossil Fuel Resources
We have talked about how dangerous the burning of fossil
fuels is in our class but we still use them. That is because
fossil fuels are a key part of Alberta’s economy.
Coal is burned in generating stations to produce about 80% of Alberta’s electrical
energy! This energy is used within our homes and workplaces. Oil and natural gas are
also very important to Alberta’s economy. This is a reason why we cannot stop using it.
It’s Cold in Here!
Both fridges and air conditioners are ___________________________; this means that it
can transfer thermal energy from one location to another at a different temperature.
Fridges and air conditioners both rely on processes such as __________________ and
_________________.
In a fridge, _________________________ are used to
remove thermal energy from food.
Refrigerants:
Thermal Energy can be Dangerous!
Thermal energy can be harmful, such as burns from a
hot object or a forest fire. Thermal energy has the
power to hurt and destroy us, our belongings, and our environment.
In factories, they must carefully store harmful chemicals in storage tanks to prevent the
chemicals from leaking into the soil and then it will drain into water sources.
The soil that is affected from the chemicals must be restored before it can be used
by anything else again. Millions of dollars are placed into programs that attempt to fix
soil to its natural state.
The __________________ of thermal energy can also be dangerous. Carbon dioxide is a
byproduct which is a greenhouse gas. This contributes to global warming. Sulfur dioxide
is also released and this can be very irritating to the eyes, nose, and throat.
Also, when a fire burns without oxygen, a gas called _____________________ is
produced. It is very dangerous because it is colorless, odorless, and it can kill you. Many
people have died from inhaling this gas. The Government of Canada encourages that
every household have a detector!