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1.3 TEST MARK SCHEME

1. (a) Shared pair of electrons 1

(b)

× ×

× ×S SC

×

×

×

×

×

×H HS

circles need not be shown

all outer electrons must be shown (1) 2

must be S, C and H, S

if omission of non-bonding electrons occurs twice, penalise first time only

non-bonding electrons neednt be shown as a pair 

(c)

× ×

                  ×

                  ×

                  ×

                  ×

C a 2 ! " 2 #

transfer of electron(s) (1)

correct charges on the ions (1) 2

(d) (i) Co$alent (1)

Ignore other words such as dative, co-ordinate and polar 

(ii) %onic (1)

(iii) &reater electronegati$ity difference in 'aCl2 or more

charge separation or reduced charge density on

 barium cation, 'a2!, or reduced polarising power (1)

'e is more electronegati$e than 'a

[8]

2. (a)

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C l ' e C l

1 * +

( 1 )

( 1 )

( 1 )

'

,

, ,

1 2 * +   ( 1 )

( 1 )

C

C l

C l

C l

C l1 * - + 2 .   ( 1 )

( 1 )

( 1 )S

,,,

,,

,

- * +

(b) / has four electron pairs round / (1)

including one lone pair (1)

' has electron pairs (1)

[11]

3. (a) (i) deficiency of electrons (1)

(or small ! recharge)

(ii) tetrahedral (1) (or symmetrical)

 bond polarities cancel (1)

(or δ ! charges cancel out)

(b) $an der 0aals (1) 1

(c) H has dipole-dipole (1)

 between molecules (1)

stronger than in CH  (1)

(inter molecular forces in H > in CH scores ast mar3)

(d) H-bonding in /H  (1)

stronger than intermolecular forces in H (1) 2

(e) Shorter (1) etc

none (1) 2[11]

4.

C l C l

,,

,,

,,

, 1 * 4 +

a n g l e ( 1 )

( a l l o w 1 * + # 1 * 5 + )

s h a p e( 1 )

s h a p e ( 1 )

- + ( 1 )

+ ( 1 )

( a l l o w 6 + # - * + )

( a l l o w 4 + # - + )

[5]

11. (a) 7endency or strength or ability or power of an atom8element8nucleus to 1

attract8withdraw electrons 8 e #  density 8 bonding pair 8 shared pair 

%n a co$alent bond 1

(tied to M1 – unless silly slip in M1)

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(If molecule/ion then = CE = 0) (NOT electron (sinul!r) for

 M1)

 Mark as 2 + 2

%ncrease in si9e or number of shells or increased shielding or bonding 1

electrons further from nucleus

"NOT #incre!se in num$er of electrons%&

:ecreased attraction for (bonding) electrons 1

( tied to M3 )

(If #ion% here' lose M !nd M) (NOT #!ttr!ction of co*!lent

$ond%)

(Inore reference to proton num$er or effecti*e nucle!r ch!re)

(b) Hydrogen bonding (full n!me) 1

:iagram shows at least one;!

H and at least one;# 

1

(If full ch!res sho+n' M, = 0)

lone pairs shown on at least one fluorine atom 1H-bond indicated, between H and a lone pair on

H , H ,

δ δδ δ! ! # #

< <

(If !toms not identified' -ero for di!)

(#.l% for fluorine m!r to M! ,)

(M! 1 if only one 2. molecule sho+n' or  2Cl sho+n)

:ipole results from electronegati$ity difference or $alues =uoted 1

(#difference% m!y $e inferred)

(3llo+ epl!n!tion – e44 . !ttr!cts $ondin electrons more

 stronly th!n 2)

QoL luorine more8$ery electronegati$e or iodine less electronegati$e 1

or electronegati$ity difference too small in H%

Comparison r!"ird# ma$ % imp&id>

H% dipole wea3er or bonding e # 

 more e=ually shared - wtte 1

(c) /aCl is ionic (lattice) 1

(Tre!t !toms/molecules !s ! contr!diction)

(3ccept #cu$ic l!ttice%)

:iamond is macromolecular8giant co$alent8giant atomic8giant molecular 1

(NOT molecul!r or tetr!hedr!l)

(Ionic/*!n der 5!!ls% = CE = 0)

(?any) co$alent8C-C bonds need to be bro3en 8 o$ercome 1

(NOT 6ust #+e!ened% etc4)

(#Co*!lent% m!y $e inferred from di!r!m)

(Tre!t di!r!m of r!phite (+ithout one of di!mond) !s !

contr!diction – lose M, $ut !llo+ M/M&)

0hich ta3es much energy or co$alent bonds are strong 1(7eferences to *!n 8er 5!!ls% $onds $re!in lose M/M)

[15]

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Mill Hill High School 4