MODULE mod7A mod7B mod7C mod7D mod7E mod7F mod7G mod7H mod7I mod7J mod7K mod7L mod8A mod8B mod8C mod8D mod8E mod8F mod8G mod8H mod8I mod8J mod8K mod8L mod9A mod9B mod9C mod9D mod9E mod9F mod9G mod9H mod9I mod9J mod9K mod9L 8ea1
8Ea1 Sorting substances
Name _____________________________ Class ____________
Name of substance
Solid, liquid or gas?
Is it an element? (yes or no)
[ observing ]
8Ea2 Elements and models 1
You can make lots of different models from a kit of building blocks. We think that everything in the Universe is made from about 100 different building blocks. These are the chemical elements. Atoms of elements are much too small to be seen. We can build models to show what we think atoms are like, and how they link together. In an element all the atoms are the same.
Here are four models made with building bricks.
1 Which models are made of pieces that are all the same shape and colour?
2 Which model has all the pieces the same shape but different colours?
3 Which model is made of pieces that are the same colour but different shapes?
4 How are the bricks in model B like the atoms in an element?
5 Which other model is most like the atoms in an element?
6 Why is model C definitely not an element?
7 Is model A like an element or not? Give a reason.
Here is a different sort of model showing the way that sulphur atoms are joined together.
8 How many atoms are shown in this model?
9 Is sulphur an element or not?
10 How do you know?
11 How is this model different from model D at the top of the page?
12 Describe one way that this model is similar to model D.
[ knowledge ]
8Ea3 Elements and models 2
You can make lots of different models from a kit of building blocks. There are millions of different substances in the Universe, but they are all made from about 100 different building blocks - the chemical elements. The differences are due to the way that the atoms of the different elements link together. In an element all the atoms are the same. Atoms of elements are much too small to be seen, even with the best optical microscopes. We can build models to show what we think atoms are like, and how they link together. Here are four models made with building bricks.
1 Describe the similarities between:
a model A and model B
b model C and model D.
2 Describe the differences between:
b model C and model D
c model A and model C.
3 How are the bricks in model B like the atoms in an element?
4 Which other model is most like the atoms in an element?
5 Does model C represent an element or not? Give a reason.
6 Is model A like an element or not? Give a reason.
7 Is sulphur an element or not? How do you know?
8 Describe the similarities and differences between this model and model D at the top of the page.
9 Scientists usually use this type of model to show the arrangements of atoms. Why is this type of model more scientifically accurate than the 'building block' models at the top of the page?
8Ea4 When were the elements discovered?
1 What is an element?
2 Draw a timeline. The years should run from 1600 to the present day.
You should also include a section on the timeline for elements which were discovered before 1600.
3 Using the table below, fit each element on to the timeline in the correct place. You could:
- write or word process name labels for each element
- draw, or cut out an illustration to show something about the element, based on the notes in the table
- add some other key events to the timeline, to show what else was happening in the world.
Name of element
Date of discovery
Notes
aluminium
1828
A common element today, which was expensive in Victorian times.
arsenic
1649
In Victorian times this was an ingredient in some medicines, though now we know it is poisonous!
boron
1808
One of the ingredients in Pyrex glass.
bromine
1826
A nasty, smelly, red liquid! The name comes from the Greek for 'stench'.
calcium
An important element for your teeth and bones.
chlorine
1774
A poisonous green gas, used as a weapon in the First World War.
einsteinium
1952
A radioactive element, named after the famous scientist Albert Einstein.
cobalt
1735
The name comes from 'Kobald', the German for goblin.
helium
1895
An element that was discovered in the Sun. 'Helios' means sun in Greek.
hydrogen
1766
An explosive gas that used to be used in airships.
hafnium
1970
An element produced inside a nuclear reactor.
mercury
ancient
The only metal that is also a liquid - sometimes known as 'quicksilver'.
phosphorus
1669
A dangerous element which glows in the dark and bursts into flames easily.
radium
1898
It used to be painted on watch dials because it glows in the dark - but we now know it can be a cause of cancer.
rhenium
1925
A metal with a melting point of over 3000 °C.
silver
Used for jewellery for thousands of years.
uranium
1789
The metal that was used in the first atomic bomb which was dropped in 1945.
tungsten
1783
The metal with the highest melting point of all - over 3400 °C.
[ knowledge, research ]
8Ea5 Where in the world? 1
Chemical elements have been discovered all over the world. In many cases, the name comes from the place of discovery.
You will need a copy of Worksheet 8Ea/6.
1 Use a key to show on the map where each of these elements comes from. You could either:
- use a colour key with a different colour for each element, or
- use a numbered key.
2 Use an atlas to look up the location of the countries if you are not sure.
Element
Place of discovery
americium
America
berkelium
Berkeley, California
californium
California
copper
Cyprus (= Cuprum in Latin)
erbium (also ytrrium, ytterbium and terbium)
Ytterby, Sweden
francium
France
germanium
Germany
Copenhagen, Denmark (Hafnia = Latin name for Copenhagen)
holmium
Stockholm, Sweden
magnesium
Magnesia, Greece
polonium
Discovered in Paris, but named after Poland, homeland of Marie Curie, who discovered it.
ruthenium
Russia (Ruthenia = Latin name for Russia)
strontium
Strontian, Scotland
8Ea6 World Map
Name _____________________________________________ Class _____________________
8Eb1 Element and symbol cards
H
S
sulphur
He
Cl
C
carbon
Ar
argon
N
nitrogen
K
potassium
O
oxygen
Ca
F
fluorine
Fe
iron
Ne
neon
Cu
Na
sodium
Zn
zinc
Mg
Kr
krypton
Al
Ag
Si
silicon
I
iodine
P
Hg
Au
gold
Pb
lead
8Eb2 Chemical bingo
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
8Eb3 Element cards
Hydrogen
An explosive gas.
Helium
A gas which does not react at all.
Lithium
A soft grey metal which floats on water and reacts easily.
Beryllium
A lightweight silvery grey metal.
Boron
A non-metal with a high melting point. Boron oxide is also difficult to melt.
Carbon
A non-metal with a very high melting point.
Nitrogen
A non-metal which is found as a gas in the air.
Oxygen
A non-metal which is found
as a gas in the air.
Fluorine
A poisonous green gas, reacts
violently with other elements.
Neon
Sodium
A soft grey metal which floats
on water and reacts easily.
Magnesium
A silvery-grey metal which reacts slowly with water and makes it 'hard'.
Aluminium
A silvery metal. Aluminium oxide has a very high melting point.
Silicon
A non-metal with a very high
melting point.
Phosphorus
A non-metal that is a solid.
Sulphur
Chlorine
A poisonous green gas, reacts easily with other elements.
Argon
Potassium
on water and reacts violently.
Calcium
A silvery-grey metal which reacts steadily with water and makes it 'hard'.
21
Scandium
A silvery metal with a high melting point.
22
Titanium
A metal with a very high melting point.
23
Vanadium
24
Manganese
A hard, silvery metal with a high melting point.
8Eb4 The Periodic Table
8Eb5 Elementary questions 1
Here are some names of elements and their symbols.
You will need a copy of Worksheet 8Eb/3 to help you answer these questions.
1 Draw lines between the names and the correct symbols.
2 After the name of each element write in whether it is a solid, a liquid or a gas. Do not write the full words but write (s) for solid, (l) for liquid and (g) for gas.
3 Write a list of all the elements above that are metals.
__________________________________________________________________________
4 Write a list of all the non-metals above that are solids.
5 Elements are sometimes named after the people who discovered them. Imagine you have just found a new element.
a What would you call it? __________________________________________________
b What would its symbol be? _______________________________________________
[ skills, knowledge ]
8Eb6 Elementary questions 2
Dimitri Mendeleev was a Russian scientist. He made a pack of cards with the chemical elements on. He wrote the names of the elements onto these cards to help him to look for patterns. He started with the lightest element. You can try out some of the ideas that Mendeleev used.
You will need a copy of Worksheet 8Eb/3. The elements on the worksheet are in order of mass. The symbols of these elements are given in the box below.
B
Be
Li
Mn
Sc
Ti
V
1 Write down the names and symbols of all the elements that are gases.
2 Write down the names and symbols of all the elements that are metals.
3 The rest of the cards should all be solid non-metals. Write a list of the elements that are solid non-metals.
4 What is the name of the lightest element on the sheet?
5 What is the name of the heaviest element on the sheet?
6 What is the name of the scientist who sorted the elements into order?
7 What country did he come from?
8 He did this work in 1869. How many years ago is this?
9 Look at the cards for elements 2, 10 and 18. How are they the same?
10 What is the similarity between elements 3, 11 and 19?
11 a How are elements 6, 14 and 22 similar to each other?
b How are they different?
8Eb7 What's in a name?
Cut out all the boxes in this table. Arrange them so that the name matches the correct symbol and description. Stick them into your book. Or copy the grid and write the text in the correct boxes.
Symbol
Origins of the name
Co
'Hydro' means water in Greek. This element is the 'water-maker' because it turns into water when it burns.
W
These dark crystals turn into a purple vapour when they are heated. 'Iodes' means purple in Greek.
Ni
The symbol comes from the Latin name 'plumbum'. It survives in modern English as plumber (a person who originally worked with lead pipes), and plumb line (a lead weight on the end of a string).
Br
The devil's element! The name is a short form of the German word 'kupfernickel' or Devil's copper.
This element is found in limestone. The Latin word 'calx' means lime.
The name comes from the German word 'kobald', meaning goblin.
This is a poisonous, smelly, red liquid. The Greek word 'bromos' means 'horrible smell'.
This was a new element when it was discovered in 1898. 'Neos' means new in Greek.
This element is a gas which flows easily from one place to another. 'Fluere' means to flow in Latin.
This is a poisonous, pale green gas. The Greek word 'chloros' means pale green.
nickel
This is a heavy metal. The name comes from the Swedish 'tung' (heavy) and 'sten' (stone).
This element was first discovered by looking at the spectrum of light from the Sun. 'Helios' means sun in Greek.
8Eb8 Playing patience with Mendeleev
Dimitri Mendeleev was the first person to sort the elements into order in a way which was convincing to other scientists. He started with a pack of cards on which he had written the names of the elements. He put these cards in order, from the lightest to the heaviest. You are going to try out some of the ideas that Mendeleev may have used.
You will need a copy of Worksheet 8Eb/3 (element cards) and a copy of the Periodic Table (Worksheet 8Eb/4).
- Cut out the cards on Worksheet 8Eb/3.
- Sort the elements into order, from number 1 to number 24.
- Deal out the pack into two rows of twelve.
- Look at the way the elements are paired up.
1 Do similar elements tend to occur in pairs?
2 Do all the metals line up together?
3 Is this a useful way of arranging the elements?
- Now deal the cards out again, using four rows of six elements. Don't forget to keep the elements in the correct number order.
4 Look down the columns of elements. How much are similar elements grouped together?
5 Do you think this arrangement is better or worse than the first one?
- Now try again, using three rows of eight elements.
6 Explain why this is a much better arrangement than the first two that you tried.
7 Give one example where the elements in a column are very similar.
8 Give one example where the elements in a column are not very similar.
9 This grid is very similar to Mendeleev's original table of the elements. Compare your grid with the modern version of the table of the elements.
a Describe one way in which your table is similar to the modern table.
b Describe one way in which your table is different from the modern version.
c Why is the change in the modern version an improvement?
[ knowledge, considering ]
8Ec1 What is a metal? 1
Test 1: Conducting heat
You will be testing six substances.
Method
1 Collect a beaker.
2 Fill it with hot water from the kettle.
3 Put all the substances into the hot water and start the stop clock.
4 Feel the ends of each of the objects.
5 When you can start to feel the heat coming through, write down the time. Use the table below.
6 If you still can't feel the heat after 5 minutes, stop the stop clock.
Apparatus
- Beaker - Kettle - Stop clock
- Iron - Copper - Plastic
- Wood - Glass - Aluminium
Recording your results
Substance
Time to feel the heat (min:sec)
Order (1 = first, 6= last)
plastic
glass
wood
Test 2: Conducting electricity
1 Set up a circuit like this:
2 Connect up the iron nail as shown in the diagram. Does the bulb light up?
3 Write your result in the table below.
4 Now try the experiment again with the other things.
Bulb on or off?
Conductor or insulator?
Test 3: How heavy?
1 Collect a block of each substance.
2 Put each one on the balance in turn.
3 Write down the mass in the table.
Mass (g)
Order of heaviness (1 = heaviest, 6= lightest)
Considering your results/conclusions
1 In this experiment the three metals are:
i
ii
iii
2 The three non metals are:
3 Are the metals good or bad conductors of heat? ------------------------------------
4 Are the metals good or bad conductors of electricity? ------------------------------
5 Are the metals usually heavy or light? -------------------------------------------
[ observing, considering ]
8Ec2 What is a metal? 2
You will be testing six substances:
- Beaker
- Kettle
- Stopwatch
- Iron
- Copper
- Plastic
- Wood
- Glass
- Aluminium
Planning
1 What do we mean when we say that something is a good conductor of heat?
2 How could you use the apparatus above to decide which of the substances in the diagram are good conductors and which are not? Write down a plan for your experiment.
3 Predict the results that you think you will get. Explain why you think you will get these results.
4 Carry out your experiment and record the results. How will you do this?
In a table?
Set up a circuit like this:
5 What do we mean when we say that something is a good conductor of electricity?
6 How could you use the apparatus above to decide which of the substances shown in the diagram are good conductors and which are not? Write down a plan for your experiment.
7 Will the good conductors of heat also be good conductors of electricity? Explain your answer.
8 Carry out your experiment and record the results. How will you do this? In a table?
You will be given blocks of each of the substances. Don't touch any of them yet!
Predicting
9 Without picking up any of the blocks, can you predict which will be the heaviest? Write down your prediction of the order for all six blocks.
10 What will need to be the same in this experiment to make it a fair test?
11 How will you do this test? What apparatus will you need?
12 How will you record your results?
13 Put the substances in order from the heaviest to the lightest. How good was your prediction?
14 Based on the results of all your experiments, which substances would you say are metals, and which are non-metals?
15 From the results of your experiments, write down:
a three properties of metals
b three properties of non-metals.
16 What other properties might let you decide whether something was a metal or a non-metal? Say what the result would be for metals in each case.
17 If the blocks in Test 3 had been different sizes, how could you take this into account so that you still had a fair comparison? What measurements would you need to make? What calculations would you need to do?
[ planning, observing, considering ]
8Ec3 What is a metal? 3
Background theory and general ideas
1 Draw a table to show the properties of metals and non-metals.
2 Which of these properties would be most suitable to test in an experiment? Explain your reasoning.
3 Which properties would be the most important for deciding if something was a metal or a non-metal? Explain your reasoning.
4 Once you have decided which properties you are going to test, write a plan of your experiment, and draw a diagram of any apparatus you might need.
5 Explain carefully how the results of each test will allow you to tell if something is a metal or a non-metal.
6 Show your plan to your teacher and get it checked before you do any practical work.
7 Carry out your tests and record all your results clearly in a neat table.
8 Use your results to decide which substances are metals, and which are non-metals. Explain your reasons carefully.
Evaluation
9 Did the tests work as well as you had planned? If not, which tests gave poor results? How might the tests be improved?
10 a Were there any results which surprised you? Which ones? (If none, go on to question 10.)
b Why were you surprised?
c Do you think the surprising results were caused because you have found out something you didn't know about metals, or because your experiment was unable to get correct results?
11 a Compare answers with other groups in the class. Do you all agree about which substances are metals?
b If you disagree, discuss reasons for the differences and write them down.
[ planning, observing, considering, evaluating ]
8Ec4 Sorting the elements
You will need Worksheet 8Eb/4, which shows the elements in the Periodic Table.
1 Colour in your copy of the Periodic Table to show the metals. Show this colour in a key.
2 Choose a different colour. Colour in the squares that contain non-metals. Add the colour to your key.
3 There are only two elements in the Periodic Table that are liquids. One is a metal, and one is a non-metal. Pick another colour, and outline the squares with these two elements in. Add this outline colour to your key.
4 Find the elements that are gases. How many gases are there in the table? Pick another colour and outline all the squares of elements that are gases. Add this colour to your key.
5 a What state are all the remaining elements in?
b How many are there?
6 Use your copy of the Periodic Table to look up the elements represented by each of these symbols. Write each symbol into the table below in the correct box.
Fe Al S Hg O Cu Zn N C He Ag Br Cl Au H Mg
Metal
Non-metal
solid
liquid
gas
8Ec5 Cube net
8Ec6 Metal or non-metal? 1
1 Match the name of the element to the correct description. One has been done for you as an example.
Description
This is a solid that can be used to make heavy masses. Some saucepans or frying pans are made from this.
This is a brown, shiny solid used for making coins or ornaments. Brass bells contain this element.
This is a yellow solid which can be found as crystals or powder. It melts easily.
This is a gas that is used to fill balloons.
This is a shiny silvery solid. It can be made into thin sheets of foil which can be used to wrap food up.
This is a shiny yellow solid that is used to make rings and necklaces. It is a very good conductor of electricity.
2 Complete these sentences to say if you think each element is a metal or a non-metal. Give a reason in each case. If you can, try to find a different reason each time.
a I think iron is a ________________ because _________________________________
______________________________________________________________________
b I think copper is a ________________ because _______________________________
c I think helium is a ________________ because ________________________________
d I think sulphur is a ________________ because _______________________________
e I think gold is a ________________ because __________________________________
f I think aluminium is a ________________ because _____________________________
8Ec7 Metal or non-metal? 2
The table gives information about a number of different elements. Look at the information in the table and answer the questions.
Melting point (°C)
Boiling point (°C)
Density (grams per cm3)
Conduction of electricity
660
2470
2.7
good
-7.2
59
3.1
poor
850
1487
1.5
carbon (graphite)
3730
4830
2.3
-101
-34.7
(1.6)
1083
2595
8.9
1063
2970
19.3
-270
-269
(0.15)
-259
-252
(0.07)
1535
3000
7.9
327
1744
11.3
lithium
180
1330
0.5
650
1110
1.7
-218
-183
(1.1)
platinum
1769
4530
21.4
1410
2360
fair
98
890
0.97
961
2210
10.5
113
445
2.0
3410
5930
19.4
420
907
7.1
Note: Figures in brackets show the density when the element is at its boiling point.
1 Write down the six elements which have the highest melting points, in order, with the highest melting point first.
2 Are most of these elements metals or non-metals?
3 a Name the elements that have boiling points below 0 °C.
b At room temperature (20 °C) what state will these elements be in?
c Are these elements metals or non-metals?
4 What state is bromine at room temperature? How do you know?
5 a Write down the names of the five elements with the highest densities.
b Are these elements metals or non-metals?
6 The density of water is 1 gram per cubic centimetre (1 g/cm3). Which two metals would float on water?
7 Which element would boil only 1 °C after it melted?
8 Based on the data in the table and your general knowledge, sort all the elements in the table into two groups: metals and non-metals. You may also find it helpful to look at the Periodic Table of the elements on page 159 of the Pupil's Book or Worksheet 8Eb/4.
8Ec8 Predicting an undiscovered element
One of Mendeleev's greatest achievements was to predict the discovery of new elements. He made a table of all the elements he knew about. He also left spaces in his table to allow for new elements to be discovered. You now have a chance to repeat Medeleev's predictions - how accurate will you be?
Here are the elements in Group 4 of Mendeleev's table. A space has been left for the missing element.
Carbon (C)
Silicon (Si)
Mystery element (?)
Tin (Sn)
Lead (Pb)
type of element
non-metal
metal
conduction of electricity
non-conductor (diamond); conductor (graphite)
semi-conductor
conductor
melting point (°C)
3850
232
mass of 1 cm3 of the solid (g)
2.2 (graphite)
7.3
chemical formula of oxide(s)
CO and CO2
SiO2
SnO2
PbO and PbO2
state of oxide(s)
both are colourless gases.
crystals (sand or quartz)
white solid
yellow solid (PbO); brown solid (PbO2)
1 Do you think the mystery element will be a metal or a non-metal? Explain your reasons.
2 How well will the element conduct electricity? Do you think the element will be:
- a good conductor?
- a semi conductor?
- a non-conductor?
Explain your reasons.
3 Make predictions for the other blank spaces in the table. In each case, explain how you arrived at your decisions.
4 Imagine that you were the person who eventually discovered the new element. Give your element a name, and a chemical symbol based on your name.
8Ed1 Element or what?
Carry out the tests described on the mystery substance X.
Record the results of each test carefully.
- 100 cm3 beaker - 2 carbon rods (electrodes)
- Dilute sulphuric acid - Test tube
- Green powder X - Bunsen burner
- Power pack (or battery) and connecting wires
- Spatula
Wear eye protection for all tests.
Test 1
1 Take a 100 cm3 beaker and fill it about one-third full of dilute sulphuric acid.
2 Add two or three spatulas of the green powder X and describe what happens.
Test 2
3 Take the solution remaining from test 1.
4 Set up the circuit as shown in the diagram.
5 If you are using a power pack, adjust the voltage to 6 V. Switch it on, and observe what happens at the carbon rods.
Test 3
6 Take a test tube, and add three spatulas of the green powder X.
7 Place the tube on a balance, and write down the mass of the tube and the powder.
8 Heat the tube over a moderate Bunsen flame for two or three minutes. Write down your observations.
9 Allow the tube to cool and measure its mass again. Has the mass gone up, down, or stayed the same?
Considering your results
1 For each test, does the evidence show that the powder X:
a is likely to be an element
b is likely to be a compound
c could be either an element or a compound?
2 Which of the tests provides the best evidence in helping you decide?
Optional extra
Can you think of any explanations for the change in mass of substance X? How could you plan a further experiment that would allow you to test your ideas? Show your plan to your teacher before you carry them out.
[ observing, considering, planning ]
8Ed2 Elements - what do you remember?
Are each of these statements true or false? For each statement that is false, write out a true version.
1 There are millions of different substances in the world.
2 There are millions of different elements in the world.
3 An apple is an element.
4 Oxygen is an element.
5 Air is an element.
6 Very few elements are liquids at room temperature.
7 Most elements are metals.
8 All gases are elements.
9 All elements are gases.
10 All the solid elements are metals.
11 There are no new elements left to be discovered.
12 Neon has only one sort of atom.
13 Humans are made up of atoms.
14 Water is an element: it is made of hydrogen and oxygen atoms.
15 Copper is an element: it only contains one sort of atom.
16 Bronze is an element because it contains copper and tin.
17 Carbon dioxide is an element because it is made of carbon and oxygen atoms.
18 All the atoms in gold are the same.
19 Hydrogen atoms are different from oxygen atoms.
20 If you heat sulphur it turns from a solid into a liquid. The atoms of sulphur in the liquid are the same as the atoms in solid sulphur.
8Ed3 Elements and compounds 1
1 Fill in the blanks by choosing the correct word or phrase from the brackets.
a Carbon, oxygen, iron and gold are all __________________ (metals/
elements/compounds).
b Things which contain only one type of atom are called __________________
(elements/compounds).
c Compounds always contain __________________ (one/more than one) type of atom.
d The chemical name for common salt is sodium chloride. There are __________________
(one/two/three) parts to the chemical name. This means it is __________________ (an element/a compound).
e Water has the formula H2O. There are two elements in water. Hydrogen is one, and
__________________ (carbon/oxygen/nitrogen) is the other. Water is
__________________ (an element/a compound). The full chemical name for water is
hydrogen __________________ (chloride/oxide/sulphate). The formula tells us that
water contains __________________ (more/less) hydrogen than oxygen.
2 Draw lines to link up the elements with the correct chemical symbols.
The first one has been done for you.
Hydrogen Br
Oxygen Mg
Helium Zn
Magnesium S
Carbon H
Nitrogen O
Bromine Kr
Zinc He
Sulphur C
Krypton N
[ knowledge, literacy ]
8Ed4 Elements and compounds 2
Here are the names of ten different substances:
carbon carbon dioxide helium lead lime
mercury oxygen salt sugar water
1 Write the names of the substances on the line at the top of each box below. Choose the names from the box above.
2 Decide if each substance is an element or a compound. Write this in the space provided in each box.
3 How did you decide if the substance was an element or compound? Draw a circle around the statement that helped you to decide. The first example has been done for you.
1 Name: Oxygen
- is a gas in the air
- is needed for burning
- can't be split up into anything simpler
- is _________________ (an element/a compound)
2 Name: ______________________
- is a liquid metal
- conducts electricity
- does not change when a current passes through it
3 Name: ______________________
- melts at a high temperature
- conducts electricity when it has melted
- splits up when a current passes through
4 Name: ______________________
- is made of carbon and oxygen
- is used by plants
- turns limewater milky
5 Name: ______________________
- is made of calcium and oxygen
- is used by farmers
- is an alkali
6 Name: ______________________
- is used in balloons
- is very light
7 Name: ______________________
- is a liquid
- gives off gases when you pass a current through it
- boils at 100 °C
- is_________________ (an element/a compound)
8 Name: ______________________
- can be melted quite easily
- conducts electricity when melted
- does not change when electricity goes through it
9 Name: ______________________
- tastes sweet
- can be white or brown
- turns black and gives off steam when you heat it
10 Name: ______________________
- can be made into rods which conduct electricity
- does not get split up when a current passes through
- is found in pencil leads
8Ed5 Elements and compounds 3
1 Look at the diagrams below.
A
D
E
a Which boxes show particle diagrams of elements? _____________________
b Which boxes show particle diagrams of compounds? _____________________
c Helium does not react with anything at all. Atoms of helium do not join up with any
other atoms. Which diagram best represents helium? _____________________
d Oxygen gas is in the form of particles which have the formula O2. Which two diagrams
show this arrangement? _____________________
e Carbon dioxide has the formula CO2. Which diagram could represent carbon dioxide?
_____________________
f Hydrogen atoms are smaller than any others. Which diagram could represent water?
Explain your answer. ____________________________________________________
g Which of the following could be the name of the substance in box C? _______________
i nitrogen ii hydrogen chloride iii carbon monoxide
iv krypton v sulphur dioxide
Explain your reasoning. __________________________________________________
8Ed6 The impossible compounds
Over 300 years ago Isaac Newton had shown that white light was a mixture of all the different colours of the rainbow. Scientists had developed this idea into the spectroscope, which allowed them to look in great detail at the spectrum of light from different sources. When some elements are heated, they give off particular colours of light. One example is sodium, which gives the orange colour that you see in street lights. These colours show up as lines in the spectrum. Each element has a different set of lines, and the pattern of lines acts like a 'fingerprint' to identify the element.
In 1868, during an eclipse of the Sun, Pierre Janssen (1824-1907) found a line in the spectrum of sunlight that did not belong to any known element. He decided that this must be a new element, which was named helium after the Greek word for the Sun, 'helios'. Just over 100 years ago, in 1895, helium was discovered on Earth. It is found in tiny amounts in the atmosphere, and also in natural gas. At about the same time, a whole family of gases like helium was discovered: argon, neon, krypton and xenon. These gases shared one remarkable property which had made them so difficult to find. They did not do any chemical reactions at all! Because of this, they were known as the inert gases, and scientists assumed that reactions of the inert gases were impossible.
In 1962, Neil Bartlett (born 1932) managed to do the impossible reactions. He was working with platinum hexafluoride, PtF6, a gas which reacts very easily. Based on the reactions that he had done, and his knowledge of the inert gases, he predicted that platinum hexafluoride would react with xenon. When he mixed the two gases together, they reacted straight away, and an orange solid was formed. He had made the first ever compound of xenon. Within a year, other compounds had been made, including three different fluorides XeF2, XeF4 and XeF6, and an oxide XeO3. This was followed by the making of krypton difluoride KrF2.
Because the gases do have a few reactions, they are often known these days as the noble gases rather than the inert gases. In the same way that the 'nobles' didn't mix with the common people, the noble gases don't react much with the other elements. Helium, neon and argon still have not been made to react with any other elements at all. These chemical reactions really are impossible ... or are they?
1 In which year was helium discovered in the Sun?
2 How many years later was it that:
a helium was discovered on Earth?
b the first compound of xenon was made?
3 Why did it take so long to find the noble gases in the atmosphere on Earth?
4 For over 50 years, scientists didn't even bother trying to make any compounds of the noble gases. Why was this?
5 The gas argon is used to fill electric light bulbs. The tungsten wire inside the bulb gets very hot when the electricity is passed through it.
a What would happen inside a light bulb if it were filled with air?
b Why is argon a good gas to use?
6 The compound XeF4 is called xenon tetrafluoride. What is the chemical name for:
a XeF2 b XeF6?
7 From the passage, find an example of:
a a scientist making observations
b a scientist drawing a conclusion
c a scientist making a prediction.
8 Imagine that you are the scientist who manages to make the first ever compound of argon. Either write a letter to a friend telling him or her about it, or write a tabloid newspaper report on the new discovery.
[ literacy, knowledge ]
8Ee1 Burning magnesium
When magnesium burns in air, there is a very bright flame and white smoke. Ash is formed. Usually the smoke rises up into the air. In this experiment you will try to catch all the smoke and ash, to find out how much
is produced.
1 When the magnesium is heated, there are three possible things that could happen to the mass:
- the white ash could have a higher mass than the magnesium
- the white ash could have a lower mass than the magnesium
- the mass of the magnesium and the ash could be the same.
a Write down your prediction.
b Explain your prediction.
- Eye protection - A strip of magnesium
- Crucible and lid - Pipe-clay triangle
- Tripod - Bunsen burner
- Emery paper - Tongs
Wear eye protection.
1 Find the mass of the crucible with the lid. Record this in your book.
2 Take the strip of magnesium. Make sure it is shiny and silver. If it needs cleaning, use a piece of emery paper to clean off any coating.
3 Coil up the magnesium so that it fits inside the crucible. Try not to coil it too tightly, so that the air will be able to get to all parts of the metal.
4 Put the coil of magnesium inside the crucible, and put the lid on. Find the mass of the crucible and magnesium together. Write it down.
5 Put the crucible into the pipe-clay triangle, and support this on the tripod, as shown in the diagram. Leave the lid off at the start.
6 Heat the crucible with a strong blue Bunsen flame.
7 When the magnesium starts to burn, use the tongs to put the lid onto the crucible. This will stop the smoke escaping.
8 About every 10 seconds, using the tongs, lift up the lid to let some air in. Try not to let any smoke out.
9 When you think that all the magnesium has burned, take the lid off and keep heating until you are sure that there are no more sparks or flames.
If more smoke is given off, you should put the lid back on again.
10 When the reaction is finished, turn the Bunsen burner off.
11 Find the mass of the crucible with the ash in it. Don't forget to put the lid on! Write down the mass.
The crucible will be very hot. Leave it for at least 5 minutes to cool down.
Considering your results/conclusion
2 a What has happened to the mass of the magnesium? Has it gone up or down?
b Using your results alone, can you be certain that this is the right answer? Why?
3 a Compare your answer with the other groups in the class. Do you all agree?
b Using the class results, can you be sure about whether the magnesium should have gone up or down in mass. Why?
4 Was your prediction correct?
5 a What has the magnesium reacted with?
b What chemical has been formed?
6 Write a word equation for the reaction. How does this equation help to explain the results from the experiment?
7 Suggest why different groups might have got different results. What mistakes might have been made?
8 Can you suggest improvements to the way the experiment was done to make the results more accurate?
[ observing, considering, evaluating ]
8Ee2 Making compounds
1 Write each of these chemicals in the correct column in the table:
carbon nitrogen carbon dioxide hydrogen oxide (water) iron hydrogen iron oxide (rust) copper sodium chloride (salt)
Elements
Compounds
2 Look at the five word equations below. Write the name of the correct product in each box. Use the list to help you.
iron sulphide sodium chloride magnesium oxide iron oxide
copper chloride
sodium + chlorine
→
magnesium + oxygen
iron + oxygen
iron + sulphur
copper + chlorine
3 Fill in the missing words to complete these word equations.
a ____________________ + oxygen → carbon dioxide
b lead + oxygen → ____________________ oxide
c copper + oxygen → copper ____________________
d tin + ____________________ → tin chloride
e sodium + chlorine → ____________________ ____________________
8Ee3 Naming compounds
1 Fill in the missing words in these word equations.
a ___________________ + oxygen → carbon dioxide
b lead + oxygen → ___________________ oxide
c copper + oxygen → copper ___________________
d tin + ___________________ → tin chloride
e sodium + chlorine → ___________________ ___________________
2 Each of the chemicals in the table has a common name as well as a proper chemical name. Fill in the blanks in this table.
Common name
Chemical name
Elements in the compound
common salt
sodium chloride
sodium, chlorine
water
hydrogen, oxygen
ammonia
nitrogen hydride
'rotten egg' gas
hydrogen sulphide
3 The table shows the names and chemical formulas of some compounds. Fill in the blank spaces in this table.
Name of compound
Chemical formula
Number of elements in the compound
Names of elements in the compound
magnesium oxide
MgO
magnesium, oxygen
potassium oxide
K2O
FeS
iron, sulphur
potassium hydroxide
KOH
calcium carbonate
CaCO3
8Ee4 An element ... or not an element?
For each of the pieces of information, decide whether:
A the substance is definitely an element
B the substance is definitely not an element
C it is not possible to tell on the evidence available.
Substance number:
1 is made of only one sort of atom
2 melts when you heat it
3 has the symbol C
4 is made of different atoms joined together
5 is a solid at room temperature
6 is made of atoms
7 has the chemical formula KF
8 gives off carbon dioxide when you heat it
9 is pure water
10 has the formula CO
11 has the symbol Co
12 has the formula O2
13 has the formula CO2
14 does not change when you heat it
15 breaks into two new materials when you heat it.
8Ee5 Chemical compounds: names and formulae
The name of a chemical compound tells us about the elements that it is made from. The simplest compounds are made of only two elements. The names of these compounds have two parts. The first part is often a metal element, and the second part is usually a non-metal, with the ending '-ide'. An example is magnesium oxide.
Many compounds are made of three or more elements. Often, one of these elements is oxygen. The names of many of these compounds have an '-ate' ending, for example copper sulphate (CuSO4).
The formula of the compound tells us:
- which elements are in the compound
- the proportions of each element present.
In copper sulphate there are four atoms of oxygen and one atom of sulphur for
each one of copper.
1 The table shows the names and chemical formulae of a number of compounds. Copy out the table and fill in the blank spaces.
CuBr2
copper, bromine
sodium nitrate
NaNO3
FeSO4
Sometimes more than one compound is made from the same elements. For example, there are several different types of nitrogen oxide. When this happens, the number of a particular type of atom is shown by using 'mono-' (one), 'di-' (two) or 'tri-' (three). For example, the compound with the formula NO is called nitrogen monoxide, and NO2 is nitrogen dioxide.
2 The table below shows some information about chemical compounds and formulae. Copy and complete the table.
Particle diagram
Number of different elements in the compound
Number of atoms in a molecule
H2O
carbon dioxide
CO
sulphuric acid
H2SO4
SO2
SO3
8Ee6 Electrolysis
1 a Copy the table below, which shows the results of some electrolysis experiments.
b Fill in the correct names of the products, labelled A and B, D and E, G and H. The names of some chemicals are listed below.
c Work out the names of the chemical that you started with, labelled C, F, and I. The names of some chemicals are listed below.
(Hint: One answer is used twice.)
chlorine copper copper chloride hydrochloric acid
hydrogen lead lead nitrate oxygen
+
-
Reaction at the positive rod
Name of product formed
Reaction at the negative rodName of product
Name of chemical formed
in the solution
bubbles of gas, which smell like a swimming pool
brown coloured coating forms on the rod
bubbles of gas which burn with a squeaky pop
bubbles of gas with no smell, makes a glowing splint light up again
G
grey metal coating forms on the rod
2 If you wanted to coat an iron nail with a layer of zinc, you could use electroplating. In this process the nail is used instead of one of the carbon rods in the circuit.
a Draw a diagram of a circuit that could be used for electrolysis experiments.
b Look back at the results table above. Which side would you put the nail: positive or negative? Explain your answer.
c What chemical could you dissolve in water to make a zinc coating stick to the iron? Choose from: iron suphate, copper chloride, zinc sulphate, magnesium nitrate. Explain your choice.
8Ee7 How much gas?
This apparatus can be used to measure the volume of gas collected during electrolysis. A pupil wrote down the volume of gas produced every minute for 10 minutes.
The results are shown in the table below. Look at the results and then answer the questions on the next page.
Time (minutes)
Volume of gas collected (cm3)
Experiment 1 Current = 1 amp
Experiment 2 Current = 2 amps
0
0.0
2.5
5.0
9.8
7.6
14.9
10.0
20.0
12.4
25.0
30.2
17.5
35.1
20.2
40.0
25.2
44.8
49.9
1 Copy and complete this sentence to show the relationship between the volume of gas and time:
'The longer the time, …'
2 Write another sentence to describe the relationship between the volume of gas and the current.
3 What is the pattern of the numbers in Experiment 2? Copy and complete this sentence:
'Every minute, the volume of gas …'
4 In Experiment 1, one of the results has been recorded wrongly. This gives a result that does not fit the pattern. A result like this is often called an anomalous result.
a Which reading is wrong?
b How do you know?
c Look at the figures in the table. Suggest what the correct reading might be.
5 Plot a graph to show the results of Experiment 2. Put the volume of gas on the vertical axis and time on the horizontal axis. Draw a single straight line of best fit through the points. Label the line 'Experiment 2'.
6 On the same set of axes, plot the results for Experiment 1. Put a ring around the result which is a mistake. Draw in the line of best fit. Label the line 'Experiment 1'.
7 Another experiment could be done with a current of 3A. Predict how much gas you would get.
a Describe your prediction in words.
b Draw another line on your graph to show your prediction. Label the line 'Prediction'.
c Explain how you worked your prediction out.
[ considering, evaluating ]
8E Summary Sheets
Atoms and 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
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
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.
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)
8E Target Sheet
Topic
Targets
Before the unit
I have learned this
I have revised this
8Ea
Know that there is a huge variety of materials.
Know how many different elements there are.
Know that all materials are made of elements combined together.
Know some of the properties of elements.
8Eb
Know the names of some chemical elements.
Know what the smallest part of an element is called.
Know how elements are different from non-elements in terms of particles.
Know how to write chemical symbols for elements correctly.
8Ec
Know how to sort things into metals and non-metals.
Know examples of some properties of materials.
Know which properties apply to metals, and which to non-metals.
Know where to find metals and non-metals in the Periodic Table.
8Ed
Know how to explain the difference between an element and a compound.
Know that new materials are formed when atoms join together in different ways.
Know how to work out the numbers of different atoms in a compound from its formula.
Know how to explain the difference between an atom and a molecule.
8Ee
Know how to work out the name of a compound from the names of the elements it contains.
Know whether some common substances are elements, compounds, or mixtures.
Know how to write word equations for reactions where elements join together to make compounds.
Know how many elements are in a compound from its chemical name.
8E Word Sheets
Word sheets that include new words from the 'Focus on:' pages are available on the Exploring Science website.
8Ea - The material world
Word
Pronunciation
Meaning
A metal which reacts easily with water.
element
All the atoms in an element are the same. A substance that cannot be split up into anything simpler by chemical reactions.
metals
Elements that are shiny, conduct heat and electricity well, and often have high melting and boiling points.
non-metals
Elements that are not shiny, and do not conduct heat and electricity well.
Periodic Table
peer-ee-od-ick
Table that shows all the elements.
Soft, shiny, reactive, silver-coloured metal.
8Eb - Elementary
alloy
A mixture of different metals.
atom
The smallest part of an element you can get.
mixture
Two or more different substances that are not joined to each other.
symbol
The letter or letters that represent an element.
8Ec - Metal detecting/Fire and brimstone
electrical conductor
Something which allows electricity to flow through it easily.
heat conductor
Something which allows heat to flow through it easily.
high melting point
Something with a high melting point has to be at a very high temperature before it melts. It is a solid at room temperature.
low boiling point
Something with a low boiling point will turn into a gas at a relatively low temperature. It can be a solid, liquid or gas at room temperature.
low melting point
Something with a low melting point turns into a liquid at a relatively low temperature. It can be a solid, liquid or gas at room temperature.
magnetic
A metal (iron, nickel or cobalt) that can be magnetised or attracted to a magnet.
properties
Ways of describing a substance.
Reflects light well.
A yellow, non-metal element. Solid at room temperature
.
8Ed - Getting it together
chemical formula
A combination of symbols and numbers that show how many atoms of different kinds there are in a particular compound.
compounds
Substances that can be split up into simpler substances.
molecule
Two or more atoms joined together.
symbol equation
A way of writing out what happens in a chemical reaction using the symbols that represent the substances involved.
8Ee - Compound interest
product
New chemical formed in a chemical reaction.
reactants
Chemicals that join together to form a new substance.
sow-dee-um klor-ide
Chemical name for common salt.