Revision
EoS Semester Exam
Grade 7
Unit 8
Mixtures
Year 7 Chemistry
Revision
Learning
objective:
Review previous work,
practice exam style
questions, complete
outstanding activities
and questions and
check understanding.
Topics to cover
1. Respiration
Did you know that, because we are preparing
for our Checkpoint, our exam might include
topics from previous years, like plants,
forces, planets and the Earth in space.
2. Properties of materials
• Dissolving; solutions and solubility
• Paper chromatography
Unit 8
3. Forces and energy
Mixtures
• Forces and motion
• Speed
describing movement
Year &
7 Chemistry
Topics to cover
4. Ecosystem
Did you know that, because we are preparing
for our Checkpoint, our exam might include
topics from previous years, like plants,
forces, planets and the Earth in space.
5. Material properties
• Atom & purity
• Weather, climate and Atmosphere
Unit 8
6. Light
Mixtures
• Galaxies and Rocks in Space
7. DietYear
and
Growth
7 Chemistry
Revision
Apparatus
and
measuring
Lab apparatus
pipette
Unit 8
Mixtures
Year 7 Chemistry
Measuring Volume
Use a measuring cylinder.
The liquid forms a curve at the top called the
meniscus.
Unit 8
Put your eye at the level of the meniscus and
Mixtures
measure
from the BOTTOM.
Year 7 Chemistry
Measuring Volume
Unit 8
Mixtures
Year 7 Chemistry
What’s the
measurement?
Measuring Temperature
Use a thermometer.
Liquid expands inside the thermometer when
it gets hotter.
Unit 8
Read temperature from the scale.
Mixtures
Year 7 Chemistry
What’s the
measurement?
Please
make
sure that
your
answers
are neat
and
complete.
50 cm³
x
thermometer
Please check your
spelling.
Measuring
Cylinder
1.
2.
3.
4.
5.
9.
10.
Unit 8
Mixtures
Year 7 Chemistry
6.
7.
8.
What would you use to
measure the mass of
powder?
What would you use to
measure 10ml of
water?
Revision
Respiration
What is the meaning
of respiration?
Think about Mrs Gren.
• The process to create the
energy they need to live.
• It usually involves exchanging
two gases - oxygen and carbon
dioxide.
Mitochondria
Mitochondria: make
energy needed to power
the cell
From Gr.6
Aerobic and anaerobic
respiration
Aerobic respiration =
with oxygen
Anaerobic respiration =
no oxygen.
Aerobic respiration
Aerobic respiration is the release
energy from glucose by
of _________
oxygen inside
reacting it with ________
living cells.
Aerobic respiration equation
Photosynthesis equation
Make sure that
you know the
word equations.
😬
Where in the cell
does respiration
Unit 8
occur?
Mixtures
Year 7 Chemistry
mitochondria
😬
What are the
products of aerobic
Unit 8
respiration?
Mixtures
Year 7 Chemistry
water and carbon dioxide
😬
Besides water and
carbon dioxide,
Unit 8respiration
Mixtures
Heat/ Energy
produces ________.
Year 7 Chemistry
Instead of completing the word equation in the blocks, rewrite the word
equation in your notebook.
nose 1.
nose
pharynx (throat)
4. pharynx
5. larynx
larynx(voice
(voicebox)
box)
trachea carries air back and forth
6. trachea
between nose/mouth and lungs
sacs
(alveoli)
sacs
/ alveoli
7.airair
RIGHT
RIGHT
LUNG 2.
LUNG
with
ribrib
with
3.
muscles
muscles
in in
between
between
LEFT
LEFT
8.
LUNG
LUNG
9.bronchi
(singular:
bronchus),
bronchioles
– branches
of bronchus
branch of trachea
diaphragm
diaphragm
10.
Is the muscle used for breathing
😬
What is the name
of the muscle that
Unit 8
helps
us breathe?
Mixtures
Year 7 Chemistry
Diaphragm
😬
What carries air
between mouth/nose
Unit 8
and lungs?
Mixtures
Year 7 Chemistry
Trachea
😬 ________ are the large air tubes
leading from the trachea to the
lungs. They carry air to the lungs.
Unit 8
Mixtures
Year 7 Chemistry
Bronchi (one bronchus)
😬
What are the air
sacs in the lungs
Unit 8
called?
Mixtures
Year 7 Chemistry
Alveoli
😬
Why do we need a
large surface area
Unit 8
inside the lungs?
Mixtures
To allow gas exchange to
happen quickly.
Year 7 Chemistry
Diffusion
•The act of spreading
or allowing to spread
freely.
•The mixing of particles
of liquids or gases so
that they move from a
region of high
concentration to one
of lower concentration.
What is the meaning of breathing?
Breathing (or
ventilation) is the
process of moving air
out and in the lungs.
Breathing in is called
inhaling, and
breathing out is
exhaling.
Breathing
😬
What happens to
the diaphragm
Unit 8
when you inhale?
Mixtures
Year 7 Chemistry
It contracts and moves
downwards.
😬
What happens to your
intercostal muscles
Unit
8 you exhale?
when
Mixtures
Year 7 Chemistry
They
relax and move (the ribs)
downwards and inwards.
Breathing Plenary
Are these
statements
true or
false?
Breathing Plenary
What is in cigarette smoke?
Effects of smoking
• Increased risk for lung
diseases.
• Increased risk for cancer
(lung, bladder, blood,
esophagus, kidney, larynx,
liver, stomach, trachea,
bronchus, etc.).
• Harms unborn babies.
Smoking
• Affects bone health.
is
• Affects gums and teeth. addictive.
Revision
Properties of
materials
Please
make
sure that
your
answers
are neat
and
complete.
diffusion
What is the difference
between a compound and
a mixture?
Compounds are formed because of
chemical bonding between two or
more elements. Mixtures are formed
when substances are physically mixed
with one another.
Solutions
• A solution is a specific
type of mixture where one
substance is dissolved
into another.
• A solution is the same, or
uniform, throughout
which makes it a
homogeneous mixture.
• Solutions are always clear.
Dissolve
What is the meaning of dissolve?
To become part of
a liquid.
Example: a solid
splits up and mixes
with a liquid to
become a solution.
Add the diagram.
Soluble and insoluble
Soluble =
solid that can dissolve.
Solution becomes clear.
Insoluble =
solid that cannot be
dissolved.
Solution becomes
cloudy.
Question
+
1.
=
2.
3.
Concentration
Diluted solution =
• a little solute has been dissolved in a solvent.
Concentrated solution =
• a lot of solute is dissolved in a solvent.
Saturated solution =
• no more solute can dissolve, and any more added solute will settle at
the bottom of the container.
Saturated solution = already
contains as much / maximum
solute as possible.
Solid / crystals will start to
appear at the bottom of the
container.
Concentration- Define…
1.
2.
3.
Conservation of mass
Conservation: A careful preservation
and protection of something /
Separating mixtures
Mixtures can be separated
using a variety of techniques.
1.
Distillation
takes advantage of
differences in boiling points.
2.
Evaporation
removes a liquid
from a solution to leave a solid
material.
3.
Filtration
removes insoluble
solid particles from a liquid/gas.
4.
Chromatography
involves the
separation of components of a
mixture - on a solid medium.
Separating mixtures
A mixture made of solid particles
of different sizes, for example sand
and gravel, can be separated by
sieving.
Magnetic separation is the process of
separating components of mixtures by using
magnets to attract magnetic materials.
Revision
Forces
and
motion
Forces can:
• Change the shape
of an object.
• Move/speed-up
an object.
• Stop/slow down a
moving object.
• Change the
direction of a
moving object.
Force diagrams
1. Weight – caused by
gravity.
2. Upthrust is a force
that pushes things
up.
3. Thrust is a force that
pushes things
forward.
Hammer and feather experiment
1.
When dropped on Earth, they hit the ground at different times.
2.
When dropped on the Moon, they hit the ground at the same time.
* The Moon has practically no atmosphere, and therefore no air resistance.
3.
So, it is not a difference in gravity, but the difference in air
resistance that made the hammer and feather hit the ground at
different times on Earth.
4.
Surface area affects how much air resistance a falling object
experiences.
* A bigger surface area will experience more air resistance.
When a skydiver falls…
When a skydiver falls…
When a skydiver opens
the parachute...
• The parachute provides a large
surface area.
• This increases the air
resistance greatly, as more air
particles hits a wider surface.
• Skydiver slows down.
What is “speed”?
Speed is a scalar quantity that refers to "how fast an object is
moving."
Speed can be thought of as the rate at which an object covers
distance. An object with no movement at all has a zero speed.
Calculating speed
Quiz
Fill in the missing words.
To solve for speed or rate, use the formula
for speed, s = d/t which means speed equals
distance divided by _____.
time
________
To solve for time, use the formula for time, t = d/s
distance _______
divided
which means time equals ________
by speed.
Please make sure that your answers
are neat and complete.
Please make sure that your answers
are neat and complete.
Please mark and correct your work.
Please make sure that your answers
are neat and complete.
Please make sure that your answers
are neat and complete.
Please mark and correct your work.
When a skydiver falls…
Constant speed (steady speed) = travel at the same speed
The ball travels the same distance each second.
deceleratin
g
Speeding up = becoming faster and faster
Because the ball travel more each second
When a skydiver falls…
A distance-time graph shows how the
distance and speed of an object changes
with time.
• This graph shows the movement of three
objects over time.
• The slope, or steepness, of each line
indicates the object's rate of speed. In
general, the steeper the slope, the faster
the object's speed.
• A straight line indicates constant speed,
whereas changes in slope at different
time intervals indicate changing speeds.
Distance / time graphs
Speed = 10m/2s = 5m/s
Speed = distance / time
Speed = 1m / 4s = 0.25m/s
Speed = 6m/3s = 2m/s
• Steady speed =
constant (same)
speed.
• The steeper the line of the
graph, the faster they are
moving = greater distance
in a short time.
• If distance does not change
for a period of time, it
means they are not
moving.
• If distance decrease,
means they are returning to
the starting point.
Distance / time graphs
Stationary – not moving
Moving away at steady speed
Accelerating
(moving faster)
Returning at steady speed
Moving away at steady
speed but slower than B
Decelerating
(moving slower)
Distance / time graphs
7.
1.
6.
3.
2.
4.
5.
1. For the blue runner, how far
did she travel in 2 seconds?
What is the speed?
2. For the red runner, how far did
she travel after 6 seconds?
3. How long does it take for the
red runner to travel 8 m? What
is the speed?
4. How long did the red runner
stop and rest?
5. Which runner runs faster?
Please make sure that your answers
are neat and complete.
Please make sure that your answers
are neat and complete.
Please mark and correct your work.
Revision
Material Property
Atoms
• The atom is the basic building
block for all matter in the universe.
• Atoms fit together with
other atoms to make up matter.
• Atoms are extremely small and
are made up of a few even smaller
sub-atomic particles: electrons,
protons and neutrons.
Revision
Light
Reflection of light
When the surface is smooth, the angle at which the ray hits the
surface is equal to the angle at which it bounces off.
Reflection of light
Complete the below sentences by choosing the
correct word from the word box. Re-write the
sentences in your notebook.
Vocabulary:
smooth
incident ray
•
•
•
•
bounces
equal
reflected ray
light ray
Reflection occurs when a _________ hits a surface and _________ off.
The light ray coming in from the source is called the __________.
The light ray bouncing off the surface is called the ________.
When the surface is ________, the angle at which the ray hits the surface
is _________ to the angle at which it bounces off.
Please mark and correct your work.
Refraction
What is “refraction”?
Refraction
Why does light refract (bend)?
Refraction
Refraction is the
bending of a ray of light.
It happens when light
passes from one
medium to another
medium with a different
(optical) density.
Refraction
Different types of matter have different densities.
Which one is more difficult for light to go through?
Refraction
• The speed of light depends on the medium through which
•
it travels.
When light enters a medium with a different optical density,
the speed of light changes, which also changes the
direction.
1.
normal
3.
incident
2.
ray
angle of
incidence
5.
4.
angle of
refraction
refracted
ray
6. emergent
7.
emergent
angle
ray
Label the
diagram.
What is refraction?
a) Light bouncing off a surface.
b) When light is absorbed by a medium.
c) The bending of light.
When light travels from a less dense medium
to a more dense medium, it will…
a) slow down and bend away from the normal.
b) slow down and bend toward the normal.
c) not bend.
When light travels from a more dense medium
to a less dense medium, it will…
a) speed up and bend toward the normal
b) speed up and bend away from the normal
c) not bend
The normal is…
a) an imaginary line parallel to the surface.
b) a curved line.
c) an imaginary line perpendicular to the surface.
The angle of refraction is…
a)the angle between the normal and the refracted ray.
b)the angle between the incident ray and the refracted ray.
b) the angle between the surface and the refracted ray.
Refraction
dense
normal
slower
less
away
faster
Remember
to mark and
correct your
work.
Dispersion
What happens when you shine a light through a prism?
• Light is refracted as it enters
the prism and it is refracted
again as it exits the prism.
• As light is refracted, it also
splits into a spectrum of
colours (rainbow). This is
called dispersion.
Colours of the spectrum
•RED
•ORANGE
•YELLOW
•GREEN
•BLUE
•INDIGO
•VIOLET
• White light is formed from the mixture of
these colours.
• Dispersion happens because the colours
are refracted differently.
• Red bends the least, violet bends the most.
• So they are split out when they exit the
prism.
Colours and wavelength
Red has a long wavelength, so it is
slowed down less when travelling
through a prism (easier to go through
particles).
Violet has a short wavelength so it is
slowed down more when travelling
through a prism (more difficult to go
through particles).
This is why some colours bend more
than others.
Primary and secondary colours of light
The three primary colours of light are red, green and
blue. These colours can be mixed in different amounts
to make all other colours.
The three secondary colours of light are magenta,
yellow and cyan. These colours are made by mixing
two primary colours.
Please mark and correct your work.
2.
3.
1.
4.
5.
Please mark and correct your work.
Video time
https://www.youtube.com/wa
tch?v=S9T0V5Mh01g&t=137s
Primary colours of light
blue
red
green
Primary and secondary colours of light
blue
magenta
red
green
Seeing colours
Why do surfaces look a specific colour?
The leaf appears green, because it
absorbs all other colours and only
reflects green.
Parts of the ladybug appear red,
because these parts absorb all other
colours and only reflect red.
Seeing colours
Red + green
Please mark and correct your work.
Please mark and correct your work.
Filters
A light filter is a
transparent filter that
reduces the light (or
some wavelengths of
the light) passing
through it.
Please make sure that your answers
are neat and complete.
Please mark and correct your work.
Please mark and correct your work.
Bye! That’s it for
now! Remember
to send photos of
your work to
your teacher.
Vietnam Australia
International School