Bonding

Question 1

co-ordinate / dative

Answer 1

covalent bond when both electrons are supplied by one atom

shown by arrow

often forms charged molecules

acceptor atom must bc electron deficient

lone pair donated by one atom to another

Question 2

crystal structure, eg. NaCl

Answer 2

high. mp

conduct electricity when dissolved or molten

brittle

general good solubility

Question 3

diamond

Answer 3

macromolecular

C bonded to 4 C

strong, hard

does not conduct electricity

conducts heat

insoluble

refracts lights; sparkles

Question 4

graphite

Answer 4

macromolecular

C bonded to 3 C

free electrons

weak bonds between layers

low density; far apart layers

high mp

insoluble- strong covalent

Question 5

how do electron pairs arrange themselves

Answer 5

repel each other

largest bond angle possible to minimise repulsion

Question 6

lone pair

Answer 6

non bonding pairs

Question 7

lone/bonding repulsion

Answer 7

L-L > L-B > B-B

Question 8

linear

Answer 8

2 electron pairs

180

Question 9

trigonal planar

Answer 9

3 electron pairs

120

Question 10

trigonal pyramidal

tetrahedral

Answer 10

4 electron pairs

no lone pairs

109.5

Question 11

trigonal pyramidal

Answer 11

4 electron pairs

1 lone pair

107

Question 12

bent

Answer 12

4 electron pairs

2 lone pairs

104.5

Question 13

trigonal bipyramidal

Answer 13

5 electron pairs

no lone pairs

120, 90

Question 14

seesaw

Answer 14

5 electron pairs

1 lone pair

102, 87

Question 15

T-shaped

Answer 15

5 electron pairs

2 lone pairs

88

Question 16

octahedral

Answer 16

6 electron pairs

no lone pairs

90

Question 17

square planar

Answer 17

6 electron pairs

2 lone pairs

90

Question 18

electronegativity

Answer 18

power of an atom to attract the pair of electrons in a covalent bond

may be unsymmetrical, produces polar bond

Question 19

most electronegative

Answer 19

Fluorine

Question 20

electronegativity across a period

Answer 20

increases

more protons
smaller radius
same shielding

Question 21

electronegativity down a group

Answer 21

decreases

increased radius
increased shielding

Question 22

permanent dipole-dipole

Answer 22

different electronegativies

polar bond

stronger than vdw

Question 23

temporary dipole / van der waals

Answer 23

electron orbitals are influenced by another charged particle

in all molecules

electrons move around, so electron density can fluctuate, so small temporary dipoles form, induces dipoles in neighbouring particles

Question 24

factors affecting vdw

Answer 24

number of electrons (increased chance of dipole formation)

shape of molecule (long chain have more sa for vdw to form)

Question 25

hydrogen bonding

Answer 25

strongest intermolecular force

form between hydrogen and nitrogen/oxygen/fluorine (most electronegative) as they have a large electronegativity difference

lone pair on N/O/F bonds with H on another molecule

large bp/mp

in ice, molecules arrange themselves in a lattice structure, so H2O molecules are further apart and less dense.

Question 26

expansion of the octet

Answer 26

3d subshell

there are more than eight electrons around one atom

forms lots of covalent bonds

Question 27

solid line

Answer 27

bonds are on the plane of the page

Question 28

solid wedge

Answer 28

bond is coming out of the plane of the page

Question 29

dotted wedge

Answer 29

projecting back behind the plane of the page

Question 30

how do you treat double bonds in bond angles?

Answer 30

same as single bonds

Question 31

how do you treat dative bonds in bond angles?

Answer 31

same as normal bonds

Question 32

why are ionic substances have high mp and bp

Answer 32

Strong or many or lots of (electrostatic) attractions

Between + and − ions

Question 33

name of simple covalent crystal

Answer 33

simple molecular

Question 34

ammonia

Answer 34

NH3