Group 1 - merittutors.co.uk...è á ZZZ VDYHP\H[DPV FR XN Question

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Group 1 Mark Scheme

Level Edexcel

Subject Chemistry

Exam Board GCSE(9-1)

Topic Groups in the Periodic Table

Sub Topic Group 1

Booklet Mark Scheme

Time Allowed: 51 minutes

Score: /42

Percentage: /100


Question Number

Answer Mark

1(a) D (1)

Question Number

Answer Acceptable answers Mark

1(b) An explanation linking two of the following

• reaction producesheat/exothermic (1)

• (sodium) has low meltingpoint (1)

• (sodium) has lowdensity/density less thanwater (1)

ignore sodium floats on water

(2)

Question Number

Answer Mark

1(c) 2Na + 2H2O 2NaOH + H2

LHS formulae (1) RHS formulae (1) balancing correct formulae (1)

ensure that 2 is subscript at most half the size of H and cases are correct

(3)


Question Number

Indicative content Mark

QWCQWC *1(d)similarities

• both in the same group/group 1/alkali metal• react in a similar way• same number of outer electrons/one outer

electron• both produce hydrogen/fizz (when reacted with

water)• both produce hydroxide/alkaline solution (when

reacted with water)

differences • potassium more reactive• potassium catches on fire/lilac flame• potassium outer electron further from nucleus• potassium has more shells• potassium has more shielding• potassium has less attraction of outer electron

by nucleus• potassium outer electron more easily lost

(6)

Level 0 No rewardable content

1-1 • a limited explanation e.g. both in group 1 because oneelectron in outer shell

• the answer communicates ideas using simple languageand uses limited scientific terminology

• spelling, puncuation and grammar are used withlimited accuracy

2 3- • a simple explanation e.g. sodium and potassium havesimilar reactions because they are in the same groupbut potassium is more reactive.

• the answer communicates ideas showing someevidence of clarity and organisation and uses scientificterminology appropriately

• spelling, puncuation and grammar are used with someaccuracy

3 5- • a detailed explanation e.g. sodium and potassiumhave similar reactions because they are both have oneouter electron but potassium is more reactive becauseits outer electron is more easily lost because it has anextra shell of electrons causing the attraction of thenucleus to be reduced

• the answer communicates ideas clearly and coherentlyuses a range of scientific terminology accurately

• spelling, puncuation and grammar are used with fewerrors


Question Number


2(a)(i) soft / low melting point / low boiling point

easily cut with a knife = soft low density malleable solid at room temp.

ignore float on water reject chemical properties

(1)

Question Number


2(a)(ii) An explanation linking

(all have) one electron in outer shell (2)

one outer electron = 2 marks

group number shows number of electrons in outer shell = 2 marks

same number of electrons in outer shell = 1 mark

incorrect number of electrons in the outer shell = 1 mark

accept outer orbit / highest energy level in place of outer shell

(2)


Question Number


2(b)(i) A description including any two of

effervescence / fizzing / bubbles (1) potassium floats (1) moves (on surface) (1) potassium forms ball / melts (1) potassium decreases in size / disappears / dissolves (1) (lilac) flame / catches fire (1) spits / explodes / sparks (1)

ignore ignites

ignore smoke

(2)

Question Number


2(b)(ii) D : 2K + 2 H2O → 2KOH + H2 (1)

Question Number


2(c) An explanation linking any two of

increasing {size /radius (of atom) / number of shells} (1) increased shielding (of outer electron) (1) less attraction for (outer) electron (1)

easier to remove (outer) electron

(2)


Question

Number

Answers Acceptable Answers Mark

3 (a) D is inert (1)

Question Number


3(b)

An explanation linking

{atoms/cations/ions} are in{layers /sheets} (1)

{ layers/sheets} can

{slide/slip/ move/roll} (overeach other) (1)

Any mention of intermolecular forces/covalent bonds/ionic bonds

(0)

Accept a diagram showing layers with labelled {atoms/cations/ions}

Ignore rows /lines/ lattice

Do not allow electrons can

slide/slip/move over each other Ignore references to delocalised

electrons

(2)

Question Number


3 (c) P Br

24/80 mass 3.1/31(= 0.1) (=0.3) (1)

3

Ar

ratio 1 (1)

formula PBr3

(1)

Allow PBr3 with no working or incorrect working (1)

PBr3 with some correct working (3) Accept Br3P

Allow TE for second and third marks e.g. P Br

80/24 (= 3.33) 31/3.1(= 10) (0)

3 1 (1)

P3Br (1)

P3Br with no working (0)

(3)


Question

Number


QWC 3(d) A description / explanation including some of the following points

Description effervescence / fizzing / bubbles float /on surface

move produce hydrogen (may be shown in word or balanced

equation) {an alkaline/metal hydroxide} solution (may be shown in word

or balanced equation)

gets smaller / disappears / dissolves reactivity increases with {increasing atomic number/ down the

group} / potassium effervesces more than sodium and lithium/ potassium moves faster than sodium or lithium

sodium and potassium melt/form a (silver-coloured) ball

hydrogen burns when potassium/ sodium react potassium gives a lilac flame/sodium gives a yellow flame

Universal Indicator added to water turns blue/purple

Explanation (group 1 metals) react by losing one electron electron is more easily lost with {increasing atomic number/

down the group} {electron/ outer shell} is further away from nucleus/ atomic

radius increases/ there are more electron shells with{increasing atomic number/ down the group}

{more shielding (of outer electron)/ less attraction between

nucleus and outer electron/ more shells between outerelectron and nucleus} with {increasing atomic number/down

the group}

(6)

Level 0 No rewardable material

1 1-2 a limited description of one or two points describing the reactions orexplaining them e.g. reactivity increases down the group.

the answer communicates ideas using simple language and uses limitedscientific terminology.

spelling, punctuation and grammar are used with limited accuracy.

2 3-4 a simple description of at least three points describing the reactions OR acombination of three points from the description and explanation e.g.

they all float on water, fizz and potassium gives a lilac flame. the answer communicates ideas showing some evidence of clarity and

organisation and uses scientific terminology appropriately. spelling, punctuation and grammar are used with some accuracy.

3 5-6 a detailed description and explanation of at least five points describing

the reactions and explaining the pattern of reactivity e.g. the metals allfizz, float and produce hydrogen, the reactivity increases down the groupbecause the outer electron is more easily lost.

the answer communicates ideas clearly and coherently and uses scientificterminology accurately.

spelling, punctuation and grammar are used with few errors.


Question Number


4(a) B potassium and caesium, copper and iron

(1)

Question Number


4(b)(i) A description linking

(regular arrangement of) positive ions /cations (1)

(surrounded by) {delocalised/sea of} electrons (1)

Any reference to molecules/molecular/intermolecular/covalent scores 0 marks overall

metal ions

reject “negative and positive particles” / positive atoms / protons

ignore descriptions of atoms in rows/ layers of particles etc

cloud of electrons ignore free

(2)

Question Number


4(b)(ii) An explanation linking

M1 electrons (1)

M2 move/flow (1)

M2 dep on M1

pass through / travel

For M2: ignore free/delocalised (electrons) ignore electricity flows ignore (electrons) vibrate ignore carry/pass the current/charge (2)


Question Number


4(c)(i) A description including any two from

floats (1)

moves (around) (1)

effervescence / fizzing / bubbles (1)

melts/changes to a ball shape (1)

becomes smaller /disappears (1)

moves (around) on the surface (2)

white smoke formed ignore gas/hydrogen given off

dissolves / explodes Ignore: burns/catches fire/ignites/flame/sparks ignore addition of indicators

(2)

Question Number


4(c)(ii) 2Na + 2H2O → 2NaOH + H2

LHS (1) RHS (1) balancing of correct formulae(1)

NaHO

ignore brackets around OH

Use of lower case h, upper case A, lower case o, or use of superscripts or large numbers inside the formulae loses 1 mark only

ignore state symbols (3)


Group 7 Mark Scheme

Level Edexcel

Subject Chemistry

Exam Board GCSE(9-1)

Topic Groups in the Periodic Table

Sub Topic Group 7

Booklet Mark Scheme

Time Allowed: 65 minutes

Score: /54

Percentage: /100


Question

Number


1(a)(i) A displacement (1)

Question Number


1(a)(ii) orange Any colour or combination of colours from brown, red, orange and yellow

Ignore shade of colours

Reject other colours combined with these e.g. yellow-green

(1)

Question

Number


1(b) C (1)

Question Number


1(c) (H2 + Br2 →) 2HBr

correct formula for HBr (1)

balancing of correct formulae(1)

Ignore state symbols

Allow BrH (1)

(2)

Question Number


1(d) [24 + 2x35.5] (1) (= 95) 95 with no working

[24 + 2x35.5] with no answer or an

incorrect answer scores (1)

(1)

Question Number


1(e) relative formula mass =[23 +19] (1) (= 42)

[(19/their relative formula

mass) x100] (1) (=45.2(%))consequential on their

relative formula mass

(19/42) x 100 (2) (= 45.2 (%)) (19/[19+23]) x 100 (2) (= 45.2

(%))

45/45.2 (%) with no working (2)

Ignore additional significant figures

Allow 42 seen in working (1) Allow (19/23) x 100 = {82.6% /

83%} (1)

(2)


Question Number


2(a)(i) C cations in a sea of electrons (1)

Question Number


2(a)(ii) (metals have) high melting point a lot of energy needed to break/overcome (metallic) bonds

energy needed to break/overcome strong (metallic) bonds

Ignore references to boiling point Reject reference to intermolecular forces/covalent (bonds) /attraction between ions/breaking ionic bonds/ breaking covalent bonds

(1)

Question Number


2(a)(iii) An explanation including two of the following points

• argon is inert/does notreact/is unreactive (1)

• because it has 8 electrons inits outer shell (1)

• metals would react in/withair/oxygen (1)

• argon will exclude air fromwelding point (1)

Ignore argon is in group 0/8 argon is a noble gas Ignore argon does not burn

does not {gain/lose/share} electrons

has a full outer shell (of electrons)

has a stable electron configuration

form (metal) oxide

prevents oxidation (2)


Question Number


2(b) 2 Fe + 3 Br2 → 2 FeBr3

M1 Correct symbol/formulae (1) M2 balancing of correct symbol/formulae (1)

Reject incorrect use of upper/lower case / subscripts for M1 but allow ECF for M2 (2)

Question Number


2(c) C – grey solid

(1)

Question Number


2(d) A explanation including

M1 order of reactivity chlorine > bromine > iodine (1)

and M2 one of the following points

• chlorine displaces bromine(from bromide) AND chlorinedisplaces iodine (from iodide)(1)

• bromine displaces iodine(from iodide) AND brominedoes not displace chlorine(from chloride) (1)

• iodine does not displacechlorine(from chloride) ANDiodine does not displacebromine (from bromide) (1)

For M1 reject reference to reactivity of halide ions eg chlorine more reactive than bromide

halogens/they decrease in reactivity down the group/table

chlorine is most reactive and iodine is least reactive

Ignore reference to displacement of halide ions eg chlorine displaces bromide

Ignore “replaces”

chlorine reacts with bromide AND iodide chlorine takes part in two (displacement) reactions

bromine reacts with iodide AND does not react with chloride bromine takes part in one (displacement) reactions

iodine does not react with chloride or bromide iodine does not take part in any (displacement) reactions

(2)


Question number

Answer Mark

3(a) Candidates relate information given to order of elements in the periodic table to predict: dark grey/black and solid/crystals (1)

Question number


*3(b) Answers will be credited according to candidate's deployment of knowledge and understanding of the material in relation to the qualities and skills outlined in the generic mark scheme.

The indicative content below is not prescriptive and candidates are not required to include all the material which is indicated as relevant. Additional content included in the response must be scientific and relevant.

AO1 (6 marks)

• order of reactivity: chlorine > bromine > iodine

The order of reactivity supported by suitable experiments from: • add (aqueous) chlorine to a solution of potassium bromide• the solution turns orange/yellow• bromine is produced / Cl2 + 2KBr → Br2 + 2KCl / Cl2 + 2Br-

→ Br2 + 2Cl-

• (so) chlorine is more reactive than/displaces bromine/oxidises bromide ions

• add (aqueous) bromine to a solution of potassium iodide• the solution turns yellow/red/ brown• iodine is produced / Br2 + 2KI → I2 + 2KBr / Br2 + 2I- → I2 +

2Br-

• (so) bromine is more reactive than/displaces iodine/ oxidisesiodide ions

• add (aqueous) chlorine to a solution of potassium iodide• the solution turns yellow/red/ brown• iodine is produced / Cl2 + 2KI → I2 + 2KCl / Cl2 + 2I- → I2 +

2Cl-• (so) chlorine is more reactive than/displaces iodine/oxidises

iodide ions

Allow use of suggested reactions which do not produce a displacement reaction, e.g. add (aqueous) bromine to a solution of a potassium chloride with suitable conclusion/explanation (6)


Level Mark Descriptor

0 No rewardable material. Level 1 1–2 • Demonstrates elements of chemical understanding, some of which is

inaccurate. Understanding of scientific ideas, enquiry, techniquesand procedures lacks detail. (AO1)

• Presents an explanation with some structure and coherence. (AO1)Level 2 3–4 • Demonstrates chemical understanding, which is mostly relevant but

may include some inaccuracies. Understanding of scientific ideas,enquiry, techniques and procedures is not fully detailed and/ordeveloped. (AO1)

• Presents an explanation that has a structure, which is mostly clear,coherent and logical. (AO1)

Level 3 5–6 • Demonstrates accurate and relevant chemical understandingthroughout. Understanding of the scientific ideas, enquiry,techniques and procedures is detailed and fully developed. (AO1)

• Presents an explanation that has a well-developed structure which isclear, coherent and logical. (AO1)

Question number

Answer Additional guidance Mark

3(c)(i) • calculates mol of Fe (1)• calculates mol of Br2 (1)• determines simplest ratio/LHS of

equation (1) • deduces formula of iron bromide

produced/RHS of equation (1)

OR • divides mass by relative atomic mass

(1)• simplest ratio (1)• empirical formula (1)• deduces LHS to obtain balanced

equation (1)

Example of calculation

mol Fe = 5.656

= 0.1

mol Br2 = ( )24

2×80=

0.15

ratio Fe:Br2 = 2  :  3/ 2Fe + 3Br2

2FeBr3/Fe2Br6

Fe Br 5.656

: 2480

0.1 : 0.3 1 : 3

FeBr3

2Fe + 3Br2 à 2FeBr3 (4)


Question number

Answer Mark

3(c)(ii) An explanation that combines identification – application of knowledge (1 mark) and reasoning/justification – application of understanding (1 mark): • bromine atoms are reduced (1)• because electrons are gained to form bromide ions (1) (2)


Question Number


4(a) Fe Cl 2.8/56 3.55/35.5 (1) 0.05 0.1 or 1 2 (1)

FeCl2 (1)

Cl2Fe

FeCl2 with no working (3)

Consequential errors:

if “upside down” ie 56 / 2.8 and 35.5 / 3.55 ratio 20 : 10 or 2 : 1 (1) empirical formula Fe2Cl (1)

allow 3 marks for 2.8 / 56 and 3.55 / 71 ratio 0.05: 0.05 or 1 : 1 empirical formula FeCl2

allow 2 marks for 2.8 / 56 and 3.55 / 71 ratio 0.05: 0.05 or 1 : 1 empirical formula FeCl

allow 2 marks for Fe

2.8/56 Cl

3.55/35.5 (1) 0.1 (0) 0.5

Fe5Cl (1) - ECF (3)


Question Number


4(b) EITHER2x23 (1) g Na makes 2x58.5 (1) g NaCl

9.2 g Na makes (2x58.5)x9.2 g NaCl 46

(1) (= 23.4 g)

OR 23 g Na makes 58.5 (1) g NaCl

9.2 g Na makes (58.5)x9.2(1) g NaCl

23(1) (1)

(= 23.4 g)

mark consequentially eg

46 (1) g Na makes (2x23+35.5) (0) g NaCl

9.2 g Na makes (2x23+35.5)x9.2 (1) g NaCl 46

(= 16.3 g)

23.4 g with no working (3) 23.4 g from any method (3) do not accept 23(.0)

mol Na used = 9.2/23 (1) (= 0.4)

mol NaCl = 0.4 (1)

mass NaCl = 0.4 x 58.5 (1)

(= 23.4 g)

Ignore units throughout unless incorrect

mark consequentially awarding 2 marks for 46.8 g,11.7 g and 16.3 g (see last example opposite).

(3)


Question Number

Indicative Content Mark

*4(c) A description, comparison and explanation including some of the following points

Order of reactivity: chlorine > bromine > iodine

Experiment

add (aqueous) chlorine to a solution of potassiumbromide

the solution turns orange/yellow bromine is produced

Conclusion/Explanation and equation:

(so) chlorine is more reactive than / displaces bromine

Cl2 + 2KBr → Br2 + 2KCl / Cl2 + 2Br- → Br2 + 2Cl-

Experiment

add (aqueous) bromine to a solution of potassiumiodide

the solution turns brown iodine is produced


(so) bromine is more reactive than / displaces iodine

Br2 + 2KI → I2 + 2KBr / Br2 + 2I- → I2 + 2Br-

Experiment

add (aqueous) chlorine to a solution of potassiumiodide

the solution turns brown iodine is produced


(so) chlorine is more reactive than / displaces iodine

Cl2 + 2KI → I2 + 2KCl / Cl2 + 2I- → I2 + 2Cl-

Allow use of organic solvents to identify halogens

Allow use of suggested reactions which do not produce adisplacement reaction eg add (aqueous) bromine to asolution of a potassium chloride with suitableconclusion/explanation

Allow use of table of suggested experiments(6)


LevelLev No rewardable content 11 - 1 2 a limited description of at least one experiment in which any

halogen solution is added to any halide solution (not of the samehalogen)

OR describes order of reactivity as Cl > Br > I

the answer communicates ideas using simple language and useslimited scientific terminology

spelling, punctuation and grammar are used with limited accuracy22 - 3 4 a simple description of at least two displacement experiments

AND

EITHER at least one correct explanation/conclusion

OR

at least one correct observation of a displacement reaction thatworks/balanced equation.

the answer communicates ideas showing some evidence of clarityand organisation and uses scientific terminology appropriately

spelling, punctuation and grammar are used with some accuracy

33 - 5 6 a detailed description of at least two displacement experiments

AND

(a total of) at least two correct explanations/conclusions

AND

at least one correct observation of a displacement reaction thatworks/ balanced equation

the answer communicates ideas clearly and coherently uses arange of scientific terminology accurately

spelling, punctuation and grammar are used with few errors


Question Number


5(a)(i) toxic / poisonous (gas) Ignore other words such as harmful / dangerous / smelly / corrosive (1)

Question Number


5(a)(ii) A description including the following points

• (damp blue) litmus (paper)(1)

• (turns red then) white /bleaches (1)

Allow use of any suitable named indicator with correct result eg • (damp) universal indicator paper

(1)• (turns red then) white (1)OR• (damp) starch iodide paper (1)• (turns) dark blue / black (1)

(2)

Question Number


5(a)(iii) making {poly(chloroethene / PVC / solvents / medicines / agrochemicals / disinfectants}

bleach / sterilising water / killing bacteria

ignore water purification / “swimming pools”

micro-organisms

(1)

Question Number


5(a)(iv) 2NaCl + 2H2O → 2NaOH + H2 + C 2

correct products (1) balancing of correct formulae (1)

NaCl + H2O → NaOH + ½ H2 + ½ Cl2

(2)


Question Number

Indicative Content Mark

QWC *5(b) A comparison including some of the following points

Comparing volumes of hydrogen and oxygen • (in each experiment) volume of hydrogen is twice volume of

oxygen• because water molecules contain twice as many hydrogen

atoms as oxygen atoms / is H2O• overall 2H2O → 2H2 + O2

Relating volumes of gases to current and time • (from experiments 1 and 2) time doubles• (from experiments 1 and 2) volumes of gases double• Volumes of gases are directly proportional to the time for

electrolysis / passage of current• (from experiments 1 and 3) as current x 1.5• (from experiments 1 and 3) volumes of gases x 1.5• volumes of gases are directly proportional to the current (6)

Level 0 No rewardable content 1 1 - 2 • a limited description of one trend e.g. increased time gives an

increased gas volume• the answer communicates ideas using simple language and uses

limited scientific terminology• spelling, punctuation and grammar are used with limited accuracy

2 3 - 4 • a simple description e.g. if the time is doubled, the volume of gas isdoubled and if the current is increased the volume of gas increases

• the answer communicates ideas showing some evidence of clarityand organisation and uses scientific terminology appropriately

• spelling, punctuation and grammar are used with some accuracy3 5 - 6 • a detailed description e.g. volume of hydrogen is twice volume of

oxygen and as time doubles, volume of gas doubles or as current x1.5, volume of gas x 1.5

• the answer communicates ideas clearly and coherently uses a rangeof scientific terminology accurately

• spelling, punctuation and grammar are used with few errors

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