notes

Question 1

what is the definition of ionic bonding?

Answer 1

strong electrostatic attraction between oppositely charged ions

Question 2

state and explain the trend in atomic radii & electrostatic attraction in group 1.

Answer 2

• atomic radii increases down the group & larger sized atom down the group
• more complete electron shells
• more distance from nucleus
• more shielding from nucleus to outer electron
• weaker electrostatic attraction

Question 3

which 2 factors affect the strength of ionic bonding?

Answer 3

• ionic radii
• charge of ion

Question 4

in which way does radius & charge of atom leads to a stronger bond?

Answer 4

• smaller radius & higher charge

Question 5

what is the trend atomic radii in a group and a period?

Answer 5

• increases down a group and decreases through a period

Question 6

why does Mg2+ have a stronger charge than Na+?

Answer 6

• higher charge
• attracting the same number of electrons
• therefore electrons are attracted more strongly & closer to nucleus

Question 7

how are cations formed and what charge do they have?

Answer 7

loses electrons, positive

Question 8

how are anions formed and what charge do they have?

Answer 8

gains electrons, negative

Question 9

why does ionic compounds have high melting temperatures?

Answer 9

large amount of energy needed to overcome electrostatic attraction in lattice

Question 10

why are ionic compounds brittle?

Answer 10

layers of ions slide over and repel ions of the same charge

Question 11

describe the electrical conductivity of ionic compounds.

Answer 11

does not conduct in solids but yes when molten

• no delocalised e- free to move in solids but ions are mobile in molten

Question 12

describe the solubility of ionic compounds.

Answer 12

only soluble in water & polar solvents, as energy needed to break is supplied by hydration of ions

Question 13

what is a covalent bond?

Answer 13

strong electrostatic attraction between 2 nuclei and the shared pair(s) of electrons between them

Question 14

what is a sigma bond?

Answer 14

single covalent

Question 15

what is a pi bond?

Answer 15

double / triple covalent bond

Question 16

which bond forms first, sigma / pi?

Answer 16

sigma

Question 17

explain the definition of bond length.

Answer 17

distance between nuclei of 2 covalently bonded atoms

Question 18

explain the definition of bond strength.

Answer 18

energy needed to break 1 mole of the bond in gaseous state

Question 19

explain the relationship between bond length & bond strength.

Answer 19

bond length decreases as bond strength increases

• higher electrostatic attraction between 2 nuclei & shared pair of e- in overlapping orbitals

Question 20

define electronegativity.

Answer 20

ability of an atom to attract a bonding pair of e- in a covalent bond

Question 21

what’s a dative covalent bond?

Answer 21

a covalent bond where an atom donates a lone pair

Question 22

what causes the shape of the ion?

Answer 22

e- pairs arrange themselves around the central atom to get minimum repulsion

Question 23

2 bond pairs, 0 lone pairs

name the shape & angle.

Answer 23

linear, 180

Question 24

3 bond pairs, 0 lone pairs

name the shape & angle.

Answer 24

trigonal planar, 120

Question 25

4 bond pairs, 0 lone pairs

name the shape & angle.

Answer 25

tetrahedral, 109.5

Question 26

5 bond pairs, 0 lone pairs

name the shape & angle.

Answer 26

trigonal bipyramidal, 90 & 120

Question 27

6 bond pairs, 0 lone pairs

name the shape & angle.

Answer 27

octahedral, 90

Question 28

2 bond pairs, 2 lone pairs

name the shape & angle.

Answer 28

bent / v-shaped, 104.5

Question 29

3 bond pairs, 1 lone pair

name the shape & angle.

Answer 29

trigonal pyramidal, 107

Question 30

should there be a small or large electronegativity difference for the bond to be covalent?

Answer 30

small (<1.7)

Question 31

where does london forces occur in?

Answer 31

all molecules

Question 32

are bigger molecules more likely to induce temporary dipoles? why?

Answer 32

yes

more electrons -> stronger london forces

Question 33

what intermolecular force forms when there is a polar molecule?

Answer 33

permanent dipole-dipole

Question 34

which specific bonds usually display dipole-dipole forces?

Answer 34

C-Cl, C-F, C-Br, H-Cl, C=O

Question 35

to which 3 atoms does hydrogen bonding occur?

Answer 35

N, O, F (3 most electronegative)

Question 36

what is the bond angle around the H atom at a hydrogen bond?

Answer 36

180

Question 37

why do unbranched alkanes have a higher boiling temperature than branched alkanes?

Answer 37

more points of contact between adjacent molecules -> more london forces

Question 38

how could it be determined if a compound is soluble in water?

Answer 38

if they could form hydrogen bonds with water molecules

Question 39

how could it be determined if compounds could dissolve in a solvent or not?

Answer 39

they would have similar intermolecular forces

Question 40

what is the definition of metallic bonding?

Answer 40

electrostatic force of attraction between positive metal ions & delocalised e-

Question 41

which 3 factors increases the strength of metallic bonding?

Answer 41

• higher number of protons
• more delocalised e-
• smaller ion

Question 42

4 bond pairs, 2 lone pairs

name the shape & angle.

Answer 42

square planar, 90