Download 19th November 2014 Dear Parent/ Carer, RE: Year 8 End of term

19th November 2014
Dear Parent/ Carer,
RE: Year 8 End of term exam and setting on 8th December
Your son has been sitting a series of end of topic assessments for the content he has covered this
term so far. Please note, as the term is not yet over, he will not have sat every assessment.
Details about your son’s performance on each of the end of topic assessments he has sat so far and
the average for that assessment in his class, will be sent home with your son this week. If your son is
below the average for the class this is an indication that there is a strong possibility he may be
moved down a set in January and if your son is well above the average this is an indication that there
is a chance that your son may move up a set in January. Please note, if your son was absent for his
end of topic assessment, his teacher will make time for him to complete it.
Your son has an exam in the hall on Monday 8th December which will cover all content that he has
been taught this term. The three homework booklets used this term detail the topics that have been
covered. Attached to this letter are details about revision sources and summary sheets for topics
taught this term.
The outcome of this test in December, along with his maths assessment, will primarily be used to set
your son in January. Please remember that setting is contextual, he will be set by comparing his
mark with the others boys marks in his half of the year group.
Please encourage your son to revise at home using the websites mentioned in his homework
booklet, the revision materials included in this letter and his CGP revision guide and workbook.
Yours sincerely,
R Hall
Miss R Hall
KS3 Coordinator for Science
[email protected]
Useful Websites:
There are plenty of websites that can help you revise the science you have been taught or to help you get ahead.
Here are some of the better ones just google them to get to the website:
BBC Bitesize KS3 Science
Skoool Science
Doc Brown KS3 Science
CGP (if you have purchased the books use the code to access the online resources)
Topic
Pages In the
CGP Revision
Guide
Health and Disease
Microbes
Electricity
Electro Magnets
Mass, Weight and Gravity
Elements, Mixtures and Compounds
Metals
Reactions of Metals
9-11, 22, 28
14
162-166
169-171
138-139, 174
62-66, 68-70
75-76,
83-84, 93-95
Displacement
96-97
Pages In the
Chapters In the
CGP workbook Exploring
science
Electronic Book
29-30, 37-39
8C
N/A
8C
202-208
7J
213-214
8J
215-216
9J
77-91
8E, 8F
95-97
8F
105-107, 120- 8F and 9F
121, 124-125
118, 126-129
9F
Revision notes for Biology Topics:
8C Summary Sheets
Microbes
Microbes (short for micro-organisms) can only be seen using a microscope. There are three main
types: viruses, bacteria and fungi. The most common fungus microbes are yeasts.
Viruses
are smaller than
bacteria
which are smaller than yeasts.
Viruses are often not considered to be living because they do not carry out any of the seven life
processes for themselves.
Bacteria and yeast are important in making foods and drinks. Yeast is used to make bread dough
rise. It uses oxygen, from the air found in pockets in the dough, for aerobic respiration. This process
produces carbon dioxide which makes the bread rise.
glucose + oxygen  carbon dioxide + water (+ energy)
(a sugar)
Yeast are also used to make beer and wine. In this case there is no air and so they use anaerobic
respiration. When yeast use anaerobic respiration it is called fermentation. The ethanol is a waste
product of this reaction.
glucose  carbon dioxide + ethanol (+ energy)
(a sugar)
The numbers of an organism in an area are called a population. In good conditions (warm, moist,
plenty of sugar) a population of yeast will grow rapidly. The population stops growing if something
runs out (eg sugar). The thing that stops the population growing is called a limiting factor.
Diseases
Some microbes cause infectious diseases (diseases that can be spread from person to person). The
microbes are said to infect you. The effects the microbes have on your body are known as
symptoms. Microbes can be spread by the air, water, touch, food, animals and sex.
Disease
Microbe that causes it
Symptoms
How it is spread
Virus
Sore throat, running nose, fever
Air
Food poisoning
Bacteria
Vomiting, diarrhoea
Food
Cholera
Bacteria
Vomiting, diarrhoea
Water
Athlete’s foot
Fungus
Sore cracked skin between the toes
Touch
Colds and flu
Some ways that diseases can be stopped from spreading are:
•
•
•
•
•
making sure sewage is treated and disposed of properly
adding chlorine to water to kill bacteria
pasteurising milk
using disinfectants, antiseptics and soaps
immunising people with vaccines.
Your body has natural defences to stop microbes getting in (eg skin, mucus in the windpipe and
nose, ciliated epithelial cells to sweep mucus along). Your body also has ways of destroying
microbes. These include:
•
•
•
•
a chemical in tears that kills some bacteria
acid in the stomach that kills some bacteria
white blood cells that engulf microbes
other white blood cells that make antibodies to help destroy microbes.
Babies do not have fully developed immune systems. Antibodies can pass through the placenta and
are found in breast milk. These help the baby to fight infections.
For many diseases, once you have had the disease (or been immunised) you will not get it again (e.g.
chickenpox). This is because the antibodies against these microbes stay in the blood.
Some diseases can be cured using antibiotics which are medicines which kill off bacteria. Some
bacteria, however, are unaffected by antibiotics – they are resistant to them.
Notes for Physics Topics:
7J Summary Sheets
Electrical circuits
Electricity is a flow of electrons. Electricity can flow through conductors but not through insulators.
Metals are good conductors of electricity.
Circuits
A complete circuit is needed for electricity to flow.
We use symbols when we draw circuits:
Component
Symbol
Component
cell
variable resistor
battery of cells
motor
bulb
ammeter
switch
fuse
Symbol
resistor
The current is the amount of electricity flowing in the circuit. The units for current are amps (A).
Current is measured using an ammeter.
The resistance of a circuit is a way of saying how easy or difficult it is for electricity to flow.
•
•
high resistance = hard for electricity to flow = small current
low resistance = easy for electricity to flow = large current
Circuits can be series or parallel circuits.
Series circuit
•
•
•
•
Parallel circuit
If one bulb breaks, all the others go off.
•
The current is the same everywhere.
If you put more bulbs in they will be dimmer, because •
it is harder for the electricity to get through. The
resistance of the circuit is higher.
•
The voltage from the cell or power pack is divided
between the components.
•
If one bulb breaks, the bulbs in the other branches
stay on.
The current splits up when it comes to a branch. The
current in all the branches adds up to the current in
the main part of a circuit.
If you add more bulbs they stay bright. It is easier for
the current to flow with more branches, because there
are more ways for the electrons to go.
The voltage is the same across all the branches of the
circuit.
Electricity and heat
•
•
•
When electricity flows through a wire, the wire can get hot.
Hot wires are used in electric fires, irons and cookers.
A fuse is a thin piece of wire that melts if too much electricity flows through it. It is
used for safety.
Electricity and your body
Electrical signals in your body travel along nerves. If an electrical current passes through your body
you may get an electric shock. This could burn you, or stop your heart or lungs working.
8J Summary Sheets
Magnets and electromagnets
Magnetism is a non-contact force. Magnets attract magnetic materials. Iron, nickel and cobalt are
magnetic materials. Mixtures, like steel, that include a magnetic material will also be attracted to a
magnet. Other metals, like aluminium, are not magnetic and will not be attracted to a magnet. Iron
oxide is a compound that is a magnetic material. It is used to make video and music cassettes and
computer discs. Magnetic materials can also block magnetism.
You can make a magnet from a piece of iron or steel.
•
•
•
•
The two ends of a bar magnet are called the north seeking pole and the south seeking
pole or north pole and south pole for short.
A north pole and a south pole attract each other.
Two north poles or two south poles will repel each other.
The space around a magnet where it has an effect is called its magnetic field.
This is the shape of the magnetic field of a bar magnet.
You can find the shape of the magnetic field using iron filings or using a plotting compass.
The Earth has a magnetic field. A compass is a small magnet that always points north. But magnetic
materials placed near a compass can change the direction that it points.
Magnets can be used to sort iron and aluminium cans for recycling. Only the iron cans are attracted
to the magnet. Magnets can also be used for holding fridge doors shut, and in compasses that sailors
or walkers use.
A wire with electricity flowing through it has a magnetic field around it. An electromagnet is a coil of
wire with an electric current flowing through it.
You can make an electromagnet stronger by:
•
•
•
increasing the number of coils of wire
increasing the size of the current (by increasing the voltage)
using an iron core.
Electromagnets can be used for lifting things. They are also used in electric bells, relays and in video
and music recording.
Electromagnets are used to make bells work.
A reed switch has two thin pieces of iron inside it. If a magnet is held near the switch, the pieces of
iron are magnetised and touch each other. A reed switch can also be switched on using an
electromagnet. Any switch that is worked by electricity is called a relay.
Relays are used to make things safer. For example, the starter motor in a car uses a high current and
needs thick wires for the current to flow through. A relay is used in a car so that the driver does not
have to touch any part of the circuit that has a high current.
9J Summary Sheets
Gravity and space
Mass and weight
The mass of something is the amount of substance or ‘matter’ it contains. It is measured in
kilograms (kg). Weight is the force of gravity pulling on a mass. It is a force, so it is measured in
newtons (N).
Gravity
Gravity is the force of attraction between two masses. The force of gravity is stronger if:
•
•
the objects have large masses
the objects are close together.
On Earth, the gravity pulls on every kilogram of mass with a force of 10 N.
Gravity is not as strong on the Moon, because the Moon has a much smaller mass than the Earth. If
you went to the Moon your mass would not change, but your weight would be less than on Earth
because the Moon’s gravity is weaker.
If a rocket travels away from the Earth, the force of gravity gets less and less as it gets further from
Earth. If it is heading for the Moon, it will eventually reach a place where the Earth’s gravity is
cancelled out by the Moon’s gravity. After that, the Moon’s gravity will be pulling it towards the
Moon.
The Sun’s gravity keeps all the planets moving in elliptical orbits around it. If there was no gravity
from the Sun, the planets would all fly off into space. The Earth’s gravity keeps the Moon in orbit
around the Earth.
Satellites
A satellite is anything that orbits around a planet. The Moon is the only natural satellite of the
Earth.
Artificial satellites can be put into orbit around the Earth. They can be used for communications
(transmitting telephone calls or television programmes), for navigation, or to take pictures of the
Earth or the planets and stars.
Satellites can also be put into orbit around other planets. They can take pictures and take
measurements, and send all the information back to Earth.
Changing ideas about the Solar System
People have known that the Earth is spherical for thousands of years, but they have only believed
that the Sun is at the centre of the Solar System for about 500 years.
Early ideas had the Earth in the centre of the Solar System, with the Sun, the planets and the stars
moving in circular orbits around the Earth. These ideas were used to make predictions about where
the planets would be in the sky, but the predictions were not very accurate.
Copernicus suggested that the Sun was in the centre of the Solar System, but his model still had the
planets moving in circular orbits. The predictions made using this model were a bit more accurate,
but there were still errors.
Kepler suggested that the planets actually move in elliptical orbits around the Sun. His model could
be used to make very accurate predictions. After Newton had worked out how Kepler’s model could
be explained using his ideas about gravity, most scientists accepted that this was the correct way of
thinking about the Solar System.
Revision Notes for Chemistry Topics:
8E Summary Sheets
Atoms and elements
Elements
An element is a simple substance that cannot be split into anything simpler by chemical reactions.
Atoms are the smallest particles of an element that can exist. Atoms of one element are all the
same, and are different from atoms of all the other elements.
There are over 100 different elements. All the elements are shown in the Periodic Table. Each
element has a chemical symbol, which is usually one or two letters. A symbol is written with the first
letter as a capital, and the second letter is small.
carbon
C
oxygen
O
nitrogen
N
hydrogen
H
gold
Au
silver
Ag
copper
Cu
aluminium
Al
Metals and non-metals
The properties of a substance are the words that we use to describe it, or measurements that we
can make on it. Metals and non-metals have different properties.
Metals
Non-metals
good conductors of heat and electricity
poor conductors of heat and electricity
shiny
dull
solids with a high melting point (except for mercury)
most are solids or gases
found on the left-hand side of the Periodic Table
found on the right-hand side of the Periodic Table
three metals are magnetic
no non-metals are magnetic
metals can burn to form alkaline oxides
non-metals can burn to form acidic oxides
flexible
brittle
Compounds
Elements can join together to make compounds. The name of the compound tells you the elements
that are in it. Compounds made from two elements always have a name which ends in ‘-ide’.
These elements join together …
… to make these compounds
carbon, oxygen
carbon dioxide
sodium, chlorine
sodium chloride
magnesium, oxygen
magnesium oxide
A chemical formula tells you the name and number of atoms in a compound. The smallest particle of
many compounds is called a molecule. Molecules are made up of atoms. Some elements are also
made of molecules. For example, a molecule of oxygen contains two oxygen atoms joined together.
The formula is O2.
Elements
Compounds
Mixtures
atoms of helium (He)
molecules of carbon dioxide (CO2)
a mixture of helium and oxygen
molecules of oxygen (O2)
molecules of water (H2O)
a mixture of carbon dioxide
and oxygen
a lump of carbon (C)
a lump of sodium chloride (NaCl)
a lump of bronze
(an alloy of copper and tin)
8F Summary Sheets
Compounds and mixtures
Elements are simple substances which cannot be split up in chemical reactions. Atoms are the
smallest particles of an element that can exist. Atoms of an element are all the same.
Each element has its own chemical symbol. For example, the chemical symbol for oxygen is O.
Some elements have their atoms joined to each other in small groups called molecules. Oxygen is an
example.
A molecule of oxygen consists of two oxygen atoms joined together.
Compounds
Elements can join together to make compounds. A compound contains two or more elements joined
together. The name of the compound tells you the elements that are in it. Compounds made from
two elements always have a name which ends in ‘-ide’.
Many compounds exist as atoms attached to each other in small groups – molecules.
A molecule of water.
The chemical formula tells you the numbers of atoms of each element in a compound. Each element
in the chemical formula is shown by its chemical symbol. For example:
A compound always contains the same elements in the same ratio.
The properties of a compound are different from the elements that make it up. For example,
hydrogen is an explosive gas and oxygen will relight a glowing splint but water is a liquid which will
put fires out.
Chemical reactions
Compounds can react chemically by mixing them with other chemicals, or by using heat or
electricity. You can tell that a chemical reaction has occurred if there is a colour change or when a
gas is given off.
Most chemical reactions also involve an energy change. This is usually in the form of heat, but can
also involve light being given off, for example, in burning (combustion).
In a chemical reaction a new substance is always formed. Most chemical reactions are not easily
reversed (they are irreversible).
Some chemical reactions take place just by mixing. When you make a solid by mixing two liquids, the
solid is called a precipitate.
Other chemical reactions need energy to start them off. This energy can be in the form of heat, light
or electricity. When you use energy to split up compounds they are decomposed.
We can write word equations to show a chemical reaction. The chemicals that you start with are
called the reactants. The chemicals at the end are called the products. For example:
magnesium + oxygen
reactants

magnesium oxide
product
Physical changes
In a physical change no new substance is formed.
Melting, evaporating, condensing and freezing are
all examples of physical changes.
For example:
Mixtures
Elements and compounds can also be mixed together. A mixture is easier to separate than the
elements in a compound. Soil, river water and sea water are examples of mixtures that occur
naturally.
Elements and compounds melt and boil at a fixed temperature. Mixtures do not have definite
melting points and boiling points.
Air is a mixture of gases – most of the air is nitrogen and oxygen. The gases in the air can be
separated by fractional distillation.
9E Summary Sheets
Reactions of metals and metal compounds
The properties of a substance are the words that we use to describe it, or measurements that we
can make on it. Metals and non-metals have different properties.
Metals …
Non-metals …
are good conductors of heat and electricity
are poor conductors of heat and electricity (except for
carbon in the form of graphite which conducts electricity)
are shiny
are dull
are solids, often with high melting points (except for
mercury)
are mostly solids or gases
are found on the left-hand side of the Periodic Table
are found on the right-hand side of the Periodic Table
are sometimes magnetic – three metals are magnetic
(iron, cobalt and nickel)
are never magnetic
form basic oxides
form acidic oxides
are rigid when thick and bendy when thin
are brittle
can be hammered into shape
cannot be hammered into shape – the solid ones break
Using metals
Metals and non-metals have different uses because of their different properties.
Aluminium is used for power lines
because it is light and it is a good
conductor of electricity.
Iron and steel are used for bridges
because they are strong and cheap.
Gold is used for jewellery because it
does not corrode and looks nice.
Metals and acids
Many metals react with acids. Some unreactive metals will only react very slowly with strong acids,
some will not react at all. Some metals are more reactive and explode when added to acid.
When a metal reacts with an acid, hydrogen gas is given off. The reaction also produces a compound
called a salt.
9F Summary Sheets
Patterns of reactivity
Metals may react with substances around them in the environment such as air,
water and acids.
Some metals react very easily or quickly. They are reactive. Other metals do not react very easily
and are described as unreactive. The most reactive metals are found on the left-hand side of the
Periodic Table. Less reactive metals are found in the centre of the Periodic Table.
Some gases are more reactive than others. In the air, oxygen is the most reactive gas. Nitrogen is
not very reactive. When metals react with the oxygen in the air they form oxides.
metal + oxygen  metal oxide
The metals that react quickly with air also tend to react with water. When metals react with water
they form hydrogen gas and a metal hydroxide.
metal + water  metal hydroxide + hydrogen
The metals that react with water also react very quickly with acids. Some metals that don’t react
with water do react with acids. When metals react with acids, they produce hydrogen and a salt.
metal + acid  salt + hydrogen
The name of the salt formed depends on the name of the acid:
•
sulphuric acid makes sulphates
•
•
nitric acid makes nitrates
hydrochloric acid makes chlorides.
Reactivity Series
Metals can be arranged in a Reactivity Series. The most reactive metals are placed at the top of the
table.
More reactive metals can displace less reactive metals from their compounds. In a displacement
reaction, the more reactive metal will form a compound, and the less reactive metal is left on its
own as the pure element.
For example, iron is more reactive than copper, so it will displace copper from a compound.
iron + copper chloride  iron chloride + copper
Zinc is more reactive than iron, so iron will not displace zinc from a compound.
iron + zinc chloride  no reaction
You can use displacement reactions to work out the position of a metal in the Reactivity Series. For
instance, zinc will displace lead from a compound, so we know that zinc is more reactive than lead.
The Reactivity Series can also be used to predict whether reactions will occur.
The reactivity of metals can be linked to their uses. Metals used for construction need to have a low
reactivity, otherwise they will corrode away. Some metals, such as aluminium, have a natural
protective oxide layer. Others, such as iron, have to be protected from corrosion, e.g. by painting.
Many low reactivity metals have been known for hundreds or thousands of years. They can be
extracted by heating their compounds in a fire.
More reactive metals are extracted by electrolysis. This means that they have
only been discovered in the last two hundred years, since the invention of the
electric battery.