topic 2 - chemical bonding

Question 1

hydrogen bond

Answer 1

-element that has to be more electronegative than hydrogen
-electrostatic attraction between hydrogen atoms bonded to small strongly electronegative atoms and the -lone pair of electrons on there
-strong bonds

Question 2

trigonal bipyramidal

Answer 2

5 bond
0 lone pairs
e.g PCl5

Question 3

tetrahedral

Answer 3

4 bond
0 lone pairs

Question 4

octahedral

Answer 4

6 bond
0 lone

Question 5

triagonal planar

Answer 5

3 bond
0 lone

Question 6

triagonal pyramidal

Answer 6

3 bond pairs
1 lone
e.g PCl3

Question 7

linear

Answer 7

2 bond
0 lone

Question 8

v-shaped

Answer 8

2 bond
1 lone

Question 9

ionic compounds properties

Answer 9

high melting point
-strong forces of attraction
brittle
-if stress is applied the layers can slide over each other and now same charged ions repel
conductor
-no free flowing ions in solid but in liquid ions are free moving so can move with the charge
soluble
energy needed can be suplied by hydration because of polarity

Question 10

ionic bonding

Answer 10

giant lattice
strong electrostatic forces between anions and cations
strong electrostatic attraction between two oppositely charged ions

Question 11

stregnth of ionic bonds

Answer 11

size of ions
-smaller -> more energy

Question 12

covalent bonding

Answer 12

non metals
share outer electrons to become more stable
strong electrostatic attraction between 2 nuclei and a bonding pair of shared electrons

Question 13

types of covalent bonding

Answer 13

sigma is stronger as there is a good overlap of s orbitals where as there is a weaker overlap of p orbitals
larger atomic radius -weaker bond
more sheilding
further from nucleus
more bonds - stronger bonds

Question 14

electronegativity

Answer 14

ability of an atom to attract a bonding pair of electrons
decreases down a group - increase in shells + sheilding
increase across a period - charge increases
larger difference in electronegativity means stronger bonds

Question 15

polar covalent bonds

Answer 15

if the two elements have the same elctronegativities the covalent bond will be equal
if they are different the density of the covalent bond will be different
the change slightly differs so it becomes a polar molecule

Question 16

discrite molecules

Answer 16

covalent molecule in which forces are weak

Question 17

dative bond

Answer 17

when an empty orbital atom overlaps with an orbital containing a non bonding pair of electrons of another atom

Question 18

london forces

Answer 18

-van der waal
-weak bonds
uneven distribution of electrons
forms temporary dipoles
this can induce dipoles in others
if more branched london forces weaker as more surface area

Question 19

electron pair repulsion theory

Answer 19

the shape of a molecule or ion is caused by the repulsion between the pairs of electrons, both bonded and lone
the electron pairs arrange themselves to minimize repulsion
lone-lone>lone-bond>bond-bond
repulsion

Question 20

dipole

Answer 20

seperation of charge

Question 21

polar

Answer 21

if the dipoles in a molecule reinforce each other the molecule has an overall dipole

Question 22

non polar

Answer 22

if the dipoles cancel each other out the molecule will have no dipole

Question 23

permenant dipole

Answer 23

not always a favourable interaction
very weak- weaker than induced

Question 24

metalic bonding properties

Answer 24

high melting temperatures
good conductivity
malleable
ductile
low ionisation energys
delocalised electrons
giant lattice

Question 25

metal properites explained

Answer 25

conduct electricity
-when a pd is applied the delocalised electrons move to +ve movment of charge
conduct heat
-free flowing electrons pass kinetic energy as cations closely packed
malleable and ductile
-when stress is applied the layers slide over each other

Question 26

diamond

Answer 26

poor electrical conductivity
no delocalised electrons
giant covalent
each carbon bonded to 4 others

Question 27

graphene

Answer 27

good electrical conductivity
delocalised electrons
single layer of hexagonal ring of carbon
bond angles of 120 between layers

Question 28

graphite

Answer 28

good electrical conductivity
delocalised electrons
hexagonal rings of carbon bonded to 3 others
bond angle of 120 between layers
london forces between layers
covalent bonds within layers
delocalised electron within layers

Question 29

difference between high and low melting/boiling

Answer 29

one is a giant covalent lattice with many strong covalent bonds
one is a simple molecular with weak london forces
more energy required to overcome the covalent bonds

Question 30

water bonding

Answer 30

oxygen more electronegative than hydrogen so has negative charge
when two join together bond angles are 180 and 104.5

Question 31

density of water

Answer 31

ice is less dense than water
more space between molecules
3d lattice in ice
hydrogen bonds are longer than covalent

Question 32

metalic bonding

Answer 32

strong electrostatic attraction between a lattice of metal cations and a sea of delocalised electrons

Question 33

why this shape

Answer 33

no of bonding
no of lone
move to minimise repulsion

Question 34

square planar

Answer 34

4 bond pairs
two lone pairs

Question 35

bond lengths

Answer 35

larger atomic radius has more shielding so less atraction to the nucleus so a longer bond length