€¦ · web view(d) over several days, the balloons shrink because the particles of gas diffuse...

KS3 EQ Elements and Compounds 98marks 75minutes

Q1. (a) The table below shows information about five elements.

(i) Which two of these elements are likely to be metals?Write the letters.

............................... and ...............................1 mark

(ii) Which element in the table is liquid at room temperature?Write the letter........................

1 mark (b) What is the chemical symbol for copper?

Tick the correct box.

Cr Cu C Co Ca 1 mark

(c) How many atoms of iron and oxygen are there shown in the formulas for FeO and Fe2O3?Complete the table below.

compound number of atomsof iron

number of atomsof oxygen

FeO Fe2O3

2 marksQ4. A teacher mixed iron filings with sulphur on a metal tray.

She heated the mixture in a fume cupboard.Sulphur is yellow. Iron filings are grey.

The mixture glowed very brightly. The teacher turned off the bunsen burner.The glow spread through the mixture.When the mixture cooled, a black solid called iron sulphide was left.(a) From this information, give one way you can tell that a chemical reaction took

place.................................................................................................................

................................................................................................................ 1 mark (b) What type of substance is each of the chemicals involved in this reaction?

Choose from:

www.SmashingChemistry.com of 17

element melting point (°C)

boiling point (°C)

conducts electricity colour

A –7 59 no brownB –218 –183 no colourlessC 1535 2750 yes silveryD 113 445 no yellowE 1083 2567 yes orange

http://www.SmashingChemistry.com/

metallic element mixture non-metallic element compound

iron ............................................................... sulphur ......................................................... iron sulphide .................................................

2 marks (c) Raj held a magnet near to each of the three chemicals. By each chemical in the table, write yes or no to show if the chemical was

magnetic. One has been done for you.

chemical Was the chemical magnetic?

sulphur iron

iron sulphide no1 mark

(d) (i) When iron is heated with sulphur, iron sulphide is formed.Give the name of the solid formed when zinc is heated with sulphur.................................................................................................................

(ii) Some fossil fuels contain sulphur.When fuels burn, sulphur reacts with oxygen.

Complete the word equation for this reaction. sulphur + oxygen → .............................................................................

2 marksmaximum 6 marks

Q5. Six groups of pupils burned magnesium in air. The magnesium reacted with oxygen toform magnesium oxide.

They recorded the mass of magnesium used and the mass of magnesium oxideformed. Their results are shown in the table.

group mass of magnesium (g) mass of magnesium oxide (g)A 3.2 5.2B 3.8 6.5C 4.2 7.0D 4.9 8.6E 5.4 8.0F 6.1 10.7



(a) Use their results to draw a graph below.• Decide the scale for each axis. • Plot the points.• Label the axes. • Draw a line of best fit.

4 marks

(b) (i) Which group’s results do not fit the general pattern?Give the letter.

1 mark (ii) How should the class deal with this ‘odd’ result?

...............................................................................................................

...............................................................................................................1 mark

(c) Use the graph to predict the mass of magnesium oxide that will be formed byburning 7.0 g of magnesium.

............. 91 mark

(d) The results show the relationship between the mass of magnesium and the massof magnesium oxide formed.

What conclusion could you draw about this relationship?...........................................................................................................................................................................................................................................................................................................................................................................

......................................................................................................................... 1 mark


mas

s of

mag

nesi

um o

xide

UN

ITS:

mass of magnesium UNITS:=


Q6. (a) The diagrams below show the arrangement of atoms or molecules in fivedifferent substances A, B, C, D and E.

Each of the circles , and represents an atom of a different element.

Give the letter of the diagram which represents:(i) a mixture of gases;

..............1 mark

(ii) a single compound...............

1 mark (b) The diagram below shows a model of a chemical reaction between two

substances.

(i) How can you tell from the diagram that a chemical reaction took placebetween substance P and substance Q?..........................................................................................................................................................................................................................

1 mark (ii) Substance P is carbon. Suggest what substances Q and R could be. substance Q ....................................................................................... substance R .......................................................................................

1 mark (iii) How does the diagram show that mass has been conserved in this

reaction?..........................................................................................................................................................................................................................

1 markmaximum 5 marks



Q7. In the 19th Century, a scientist called John Dalton used symbols to represent atoms. The symbols he used for atoms of three different elements are shown below.

The diagrams below show different combinations of these atoms.

(a) (i) Give the letter of the diagram which shows a mixture of two elements................

1 mark (ii) Give the letter of the diagram which shows a mixture of two compounds.

...............1 mark

(iii) Give the letter of the diagram which shows a mixture of an element and a compound................

1 mark (b) Give one difference between a compound and a mixture.

.....................................................................................................................

.....................................................................................................................

.....................................................................................................................1 mark

(c) (i) Suggest a name and formula for the substance represented in diagram B.name ...........................................................formula ...............

1 mark (ii) Suggest a name and formula for the substance represented in diagram D.

name ...........................................................formula ...............

1 markmaximum 6 marks



Q8. Chris has two rubber party balloons. One is filled with air and the other is filled with helium.Both balloons contain the same volume of gas.

(a) (i) Explain why the helium balloon rises...........................................................................................................................................................................................................................

1 mark (ii) Explain why the air balloon drops to the ground.

.............................................................................................................

.............................................................................................................1 mark

(b) The chemical symbol for helium is He.Explain why air does not have a chemical symbol or formula...........................................................................................................................................................................................................................................

1 mark (c) The diagram below shows seven arrangements of particles.

The two party balloons are coated with a thin layer of aluminium.Give the letter of the diagram which best represents the particles in:(i) the helium gas; .......................

1 mark(ii) the air; .........................

1 mark(iii) the thin layer of aluminium. .........................

1 mark



(d) Over several days, the balloons shrink because the particles of gas diffuse through the balloon and escape. The helium balloon shrinks more quickly than the air-filled balloon.Answer the following questions in terms of particles.(i) Why does helium escape more quickly than air from a balloon?

.............................................................................................................

.............................................................................................................1 mark

(ii) A rubber balloon coated with aluminium takes longer to shrink than a rubber balloon without an aluminium coating.Suggest a reason why gas particles diffuse more slowly through aluminium than through rubber...........................................................................................................................................................................................................................

1 markQ9. Marie mixed 5 g of carbon with 5 g of lead oxide.

She heated the mixture strongly for 15 minutes in a fume cupboard.

After 15 minutes, Marie found some shiny beads in the mixture. (a) (i) Marie collected all the shiny beads from this experiment.

How could she test them to show they were metal?……………..……………………………….…………………..……….…………………..……………………………….…………………..……….……

1 mark(ii) Marie’s test showed that the tiny beads were metal.

What metal were the beads likely to be?……………..……………………………….…………………..……….……

1 mark (b) Marie also expected carbon dioxide to be formed in this experiment.

(i) In carbon dioxide, what element is combined with carbon?……………..…………….……

1 mark(ii) Where, apart from the air, did this element come from in this experiment?

……………..…………….……1 mark

(c) Give one safety precaution Marie should take during this experiment.……………..……………………………….…………………..…………………………………..……………………………….…………………..……………………

1 mark



Q10. The diagrams represent the arrangement of atoms or molecules in four different substances, A, B, C and D.

not to scale Each of the circles, , and represents an atom of a different element.

(a) (i) Which substance is a compound?…………

1 mark(ii) Which substance is a mixture?

…………1 mark

(iii) Which two substances are elements?………… and …………

1 mark (iv) Which two substances could be good thermal conductors?

………… and …………1 mark

(v) Which substance could be carbon dioxide?…………

1 mark (b) The following experiment was set up. Test-tubes containing substances B and C were

placed together as shown. The substances did not react.They were left for five minutes.

(i) How many molecules are there in the mixture compared to the total number in substances B and C?……………………………………….……………………………………….

1 mark



(ii) Complete the diagram which is a model of this experiment.

1 markQ11.

(a) From the substances named above, give:(i) the name of a metal;

.............................................................................................................1 mark

(ii) the name of an element which is a non-metal;.............................................................................................................

1 mark (iii) the name of an element which will rust;

.............................................................................................................1 mark

(iv) the name of a compound..............................................................................................................

1 mark (b) When magnesium and sulphur are heated together, they react.

Write the name of the compound which is formed when magnesium reacts with sulphur.......................................................................................................................

1 markQ12. A section of the periodic table of elements is shown below.

(a) Where in this section of the periodic table are the metals found?......................................................................................................................

1 mark



(b) Sodium chloride is formed when sodium and chlorine combine together in a chemical reaction.Write the symbols for sodium and chlorine.sodium …………………………………..chlorine …………………………………..

2 marks (c) The formula for a substance is MgS. What is the name of this substance?

......................................................................................................................1 mark

(d) Give the name of one element in the table above which is a gas at room temperature and in which the atoms are joined together in molecules.......................................................................................................................

1 markMaximum 5 marks

Q13. The diagrams represent the way 'atoms' are arranged in six chemical substances.Each 'atom' is represented by a circle.The 'atoms' are labelled with their chemical symbols.

(a) (i) Which diagrams represent the structures of chemical elements?Write the numbers..............................................................................................................

1 mark(ii) Explain how you made your decision.

.............................................................................................................

.............................................................................................................1 mark

(b) Give the formulae of two of the compounds represented in the diagrams.1. .................................................................................................................2. .................................................................................................................

2 marks (c) Give the name of substance 6.



......................................................................................................................1 mark

(d) Give the names of the chemical elements whose atoms can be represented by the following symbols.C ….………..……….……..…………………………………………………..…Cl ….………..……….……..…………………………………………………..…Cu ..………..……….……..…………………………………………………..…..

3 marksQ14. Air is a gas at room temperature. The chemical formulae below show some of the substances

in the air.Ar CO2 H2O N2 Ne O2

(a) Put these formulae in the correct columns in table A to show which substances are elements and which are compounds.

table A

1 mark (b) Put the formulae in the correct columns in table B to show whether the formula of each

substance represents an atom or a molecule.table B

1 mark (c) The coldest possible temperature is ‘absolute zero’, which is –273°C. As air is cooled

towards absolute zero it liquefies. Table C gives the boiling points of the substances in air.table C

A sample of air at a temperature close to absolute zero is allowed to warm up.



Which substance boils first?........................................

1 mark (d) Each particle of neon can be represented by a circle. Carefully complete the diagrams below to show the arrangement of particles in neon

gas and liquid neon.

Use circles about in size.

4 marks The porous pot shown in diagrams 1 and 2 lets gas molecules pass through the walls. In

diagram 2 a beaker containing hydrogen is placed over the porous pot. The water levels in the U-tube quickly change.

Four statements about the movement of gas molecules are given below.A – no molecules are moving into or moving out of the porous potB – same number of gas molecules are moving into the porous pot as are moving outC – more gas molecules are moving into the porous pot than are moving outD – fewer gas molecules are moving into the porous pot than are moving out

(a) Which statement, A, B, C or D, applies to:(i) Diagram 1? .........................................................................................

1 mark(ii) Diagram 2 just after the beaker is put in position?...............................

1 mark (b) What does the experiment suggest about the average speed of hydrogen molecules

compared with the average speed of molecules in the air?Hydrogen molecules .....................................................................................

1 mark (c) The beaker is removed from around the porous pot.

(i) How does the water level in the left hand part of the U-tube change?.............................................................................................................

(ii) Explain your answer in terms of the movement of molecules...........................................................................................................................................................................................................................

1 mark (d) Air contains oxygen, nitrogen, argon, some water vapour, and a little carbon dioxide.



Complete each row in the following table by ticking one box and by stating the number of atoms in one molecule of the substance.

The first row has been done for you.

4 marksQ16. There are millions of different substances that make up our world. All these substances are

made from chemical elements.(a) What is an element?

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (1)

(b) Many substances are compounds. What is a compound?....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................

(2)

Mark Scheme:M1. (a) (i) • C and Eboth answers are required for the markanswers may be in either order

1 (L5) (ii) • A

1 (L5) (b) • Cu if more than one box is ticked, award no mark

1 (L6) (c) •

number ofatoms of iron

numbers ofatoms of oxygen

1 12 3

for all four numbers correct, award two marksfor two or three numbers correct, award one markfor one number correct, award no marks

2 (L5)[5]

M2. (a) • true false

for all three correct boxes ticked, award two marks

for any two correct, award one mark2 (L6)

(b) • evaporate the water or evaporationaccept ‘heat it’accept ‘it goes from liquid to gas’accept ‘boiling’do not accept an incorrect use of evaporation,e.g. ‘she evaporates salt from sand’

1 (L5) • condense the water vapour or condensationaccept ‘it goes from gas to liquid’do not accept ‘it condenses to water vapour’

1 (L5)accept, for two marks, ‘distil or distillation’accept, for one mark, ‘condensation then evaporation’



(c)

all three lines are required for one markif more than one line goes from any one box,do not award the mark

1 (L5)

all three lines are required for one markif more than one line goes from any one box,do not award the mark

1 (L6)[6]

M4. (a) any one from• the mixture glowedaccept ‘the temperature increased’• there was a colour change• a black solid formed• a new substance has been formedaccept ‘a compound or iron sulphide was formed’accept ‘there is no longer any sulphur or yellowor iron or grey’

1 (L6) (b) • iron: metallic elementaccept ‘metal’• sulphur: non-metallic elementaccept ‘non-metal’• iron sulphide: compoundif all three answers are correct, award two marks

if two answers are correct, award one mark2 (L5)

(c) • sulphur: no• iron: yesboth answers are required for the mark

1 (L5) (d) (i) • zinc sulphidedo not accept ‘zinc sulphate’

1 (L6)(ii) • sulphur dioxideaccept ‘sulphur oxide’ or ‘sulphur trioxide’

1 (L6)[6]

M5 (a) • X-axis: mass of magnesium (g)• Y-axis: mass of magnesium oxide (g)both labels are required for the mark units are required for the mark pupils can gain credit for correct responses to otherparts if the axes are wrongly labelled or magnesiumis on the Y-axis and magnesium oxide is on the X-axis

1 (L7)• reasonable scalesaccept a scale of 1 g or 2 g per 5 small squaresscale need not begin at zero

1 (L7)• reasonably accurate plotting of all pointsall points plotted to ± 1 small square

1 (L7)• a line of best fit drawn

1 (L7) (b) (i) E

1 (L7)(ii) any one from• ignore it in drawing the line of best fitaccept ‘ignore it’• they could predict the figure from the line of best fitaccept ‘they could use the graph line’• they should repeat the readingaccept ‘check it’pupils can gain credit for a response which suggests theyshould predict the correct value from the patternor ignore the anomalous results or repeat the reading

1 (L7) (c) a number from 11 to 13accept a value consistent with the line of best fitthe unit is not required for the mark

1 (L6) (d) any one from• the greater the mass of magnesium burned the greater the massof oxide formed• the magnesium and oxygen react in fixed proportions• the mass of magnesium oxide formed is proportional to the massof magnesium burned• the greater the mass of magnesium the



greater the mass of oxygenthat combines with it

1 (L6)[8]

M6. (a) (i) B1 (L7)

(ii) D1 (L7)

(b) (i) any one from• a compound or a new substance has been formedaccept ‘the ratio is always 1P to 2Qs’accept ‘the atoms or particles have joined’• R or the product is a new substanceaccept ‘the elements have joined’

1 (L7) (ii) substance Q: oxygen substance R: carbon dioxideboth answers are required for the mark

1 (L7) (iii) the same numbers of each type of atom are presentaccept ‘the same number of atoms is present’accept ‘the same particles or same numberof particles are present’accept ‘there is the same amount of each element’do not accept ‘the same number of molecules is there’‘the same amount of elements’ is insufficient

1 (L7) [5]

M7. (a) (i) A1 (L7)

(ii) E1 (L7)

(iii) C1 (L7)

(b) any one from• a compound contains two or more elements chemically combinedor bondedaccept ‘a compound contains different elementsor atoms of different types joined together’do not accept ‘a compound contains twoor more atoms joined together’• a mixture contains two or more elements or compounds or substances not chemically combined or bondedaccept ‘a mixture can be separated by physical means’‘a mixture can be separated’ is insufficient

1 (L7) (c) (i) any one from• name: oxygen formula: O2

• name: hydrogen formula: H2

• name: nitrogen formula: N2

• name: chlorine formula: Cl2accept any other element which exists as diatomicmolecules in the gaseous stateboth the name and formula are required for the markdo not accept ‘O’ or ‘H’ or ‘N’ or ‘Cl’

1 (L7) (ii) any one from

• name: carbon dioxide formula: CO2

• name: water formula: H2O• name: sulphur dioxide formula: SO2

• name: nitrogen dioxide or nitrogen oxide formula: NO2

accept any compound with the formula XY2,eg magnesium chloride MgCl2both the name and formula are required for the mark

1 (L7)[6]

M8. (a) (i) helium is less dense than airaccept ‘helium is lighter than air’accept ‘the upthrust on the helium balloon isgreater than the weight of the balloon’

1 (L7)(ii) any one from• the air in the balloon is denser than the air in the roomaccept ‘the air in the balloon is compressed’• the rubber has weightaccept ‘rubber is heavier than air’accept ‘the rubber is denser than air’accept ‘the upthrust on the air balloon isless than the weight of the balloon’

1 (L7) (b) any one from• air is a mixtureaccept ‘air contains different gases’• air is not a single element or compound‘air is not a single substance’ is not sufficient 1 (L7) (c) (i) B

1 (L7)(ii) C

1 (L7)(iii) G

1 (L7) (d) (i) any one from• helium particles are smalleraccept ‘molecules’ or ‘atoms’ for particles• helium particles move faster

1 (L7) (ii) any one from• aluminium particles or atoms are closer together• rubber particles or molecules are further apartaccept ‘rubber particlesor molecules have bigger gaps between them’

1 (L7)[8]

M9. (a) (i) any one from• test them in a circuit• see if they conduct electricity• add acid to see if hydrogen is produced

1 (L5)(ii) leadaccept ‘malleable’ or ‘ductile’

1 (L5) (b) (i) oxygen

1 (L5)(ii) lead oxideaccept ‘the oxide’accept ‘the mixture’



do not accept ‘plants’1 (L6)

(c) any one from• wear gogglesaccept any other appropriate safety measure• wear a lab coat• use a heat-proof mat• tie her hair backdo not accept ‘use a fume cupboard’

1 (L5)[5]

M10. (a) (i) C1 (L7)

(ii) D1 (L7)

(iii) A and Banswers may be in either orderboth answers are required for the mark

1 (L7)(iv) A and Danswers may be in either orderboth answers are required for the mark

1 (L7)(v) C

1 (L7) (b) (i) the sameaccept ‘seven’

1 (L7)(ii) a random, mixed arrangement of both types of molecule should bedrawn with the molecules not touching each other

1 (L7)[7]

M11. (a) (i) any one from• gold• iron• magnesium

1 (L3) (ii) any one from• sulphur• phosphorus

1 (L4) (iii) iron

1 (L3) (iv) iron sulphide

1 (L5) (b) magnesium sulphidedo not accept ‘magnesium sulphite’or ‘magnesium sulphate’

1 (L5)[5]

M12. (a) the three columns on the left hand sideaccept ‘the first three columns’ or ‘ on the left’

1 (L7) (b) Na

1 (L7) Cl

1 (L7) (c) magnesium sulphidedo not accept ‘magnesium sulphite’or ‘magnesium sulphate’

1 (L7) (d) any one from

• hydrogen• nitrogen• oxygen• fluorine• chlorinedo not accept symbols

1 (L7)[5]

M13. (a) (i) 1accept ‘C’3accept ‘O’5accept ‘S’answers may be in any orderall three answers are required for the mark

1 (L7)(ii) they contain only one type of atom or symbol or letter

1 (L7) (b) any two from• CO2

accept ‘O2 C’• CH4

accept ‘H4C’• NaClaccept ‘Cl Na’ or ‘Na18Cl18’do not accept names of compounds

2 (L7) (c) sodium chloride or saltdo not accept ‘NaCl’

1 (L7) (d) carbon

1 (L7) chlorinedo not accept ‘chloride’

1 (L7) copperanswers must be in the correct order

1 (L7)[8]

(a)element compound

ArN2

NeO2

CO2

H2O

all six formulae are required for the mark

1 (L7) (b)

atom moleculeArNe

N2

O2

CO2

H2O

all six formulae are required for the mark

1 (L7) (c) Ne or neon



1 (L7) (d) up to ten randomly arranged particles spaced throughout the box

accept just one particledo not accept an empty box

1 (L7)most of the particles are not in contact with each other

1 (L7)the box almost full of particles of neon, more than 50% of whichare touching each other

1 (L7)the particles are randomly arranged

if the level of liquid is drawn then accept the circlesdrawn correctly below the liquid level

1 (L7)[7]

M15. (a) (i) Bif more than one letter is given award no mark

1(ii) Cif more than one letter is given award no mark

1 (b) are faster or quicker

1 (c) (i) goes down or decreasesaccept ‘goes back to where it started’or ‘goes back to diagram 1’ or ‘goes to same level’

1 (ii) more gas molecules were going out of the porous pot thangoing in or fewer molecules were going in than coming outaccept ‘hydrogen can escape quicker than air can get in’do not accept ‘pressures equalised’

1

(d)

substance it is anelement

it is acompou

nd

it is amixtur

e

number of atoms in one

moleculecarbon dioxide √ 3oxygen √ 2

if more than one box is ticked in either rowaward no mark for that part, although themark for the number of atoms may still be awarded

4[9]

M16. (a) a substance which contains one type of atomor a substance that cannot be broken downinto anything simpler for 1 mark

1 (b) more than one element/more than one type of atomcombined/join together/bonded for 1 mark each

2[3]



€¦ · web view(d) over several days, the balloons shrink because the particles of gas diffuse...

Documents