bonding and structure (2)

Question 1

one way in which diamond differs from graphene and graphite

Answer 1

poor electrical conductivity

Question 2

what is the trend in boiling temperatures of hydrogen halides

Answer 2

hydrogen chloride-> hydrogen iodide increases as size of halogen atoms increases (more electrons) which increases the strength of the London forces
hydrogen fluoride has a permanent dipole

Question 3

what happens when ammonia gas reacts with hydrogen chloride gas

Answer 3

acid base

Question 4

what is a metallic bond

Answer 4

electrostatic force of attraction between positively charged metal ions and delocalised sea of electrons

Question 5

what is an ionic bond

Answer 5

electrostatic force of attraction between oppositely charged ions

Question 6

what is a covalent bond

Answer 6

electrostatic attraction between two nuclei and the shared pair of electrons

Question 7

which has higher melting temperatures, group 1 or 2

Answer 7

group 2:
-higher charge so electrostatic forces harder to overcome as electrons more attracted to nucleus
-smaller ionic radius due to added electron increasing attraction to nucleus, harder to overcome forces

Question 8

which has higher melting temperatures, period 1 or 2

Answer 8

period 1: smaller ionic radius

Question 9

what do metals and acid make

Answer 9

hydrogen gas and salt

Question 10

what do metals and water make

Answer 10

metal hydroxide and hydrogen gas

Question 11

why do ionic compounds have high melting temperatures

Answer 11

because each ion is surrounded by multiple other ions so there are a large number of forces to be overcome, ionic bonds require more energy to break

Question 12

why do ionic compounds conduct in solution/when molten

Answer 12

when solid there are no free ions so unable to carry charge
when dissolved in solution ions are free to move and carry charge

Question 13

properties of ionic compounds

Answer 13

-hard solids
-soluble in water
-brittle

Question 14

what is ionic bond strength affected by

Answer 14

1) higher charge on cation/anion = stronger forces
2) closer packed ions = stronger forces
3) geometry

Question 15

evidence that ions exist

Answer 15

electrolysis, migration of ions
physical properties: high melting temp + solubility in water required

Question 16

what are valence electrons

Answer 16

electrons in the outer shell of an atom/ion

Question 17

what is a lone pair

Answer 17

pair of electrons not used in bonding

Question 18

what is a dative covalent bond

Answer 18

a covalent bond with both electrons in the shared pair provided by one atom

Question 19

how does bond length affect bond strength

Answer 19

shorter bonds are stronger as the atoms are held closer together so forces of attraction are greater, requiring more energy to overcome

Question 20

what are the 3 intermolecular forces

Answer 20

London forces
permanent dipole - permanent dipole interactions
hydrogen bonds

Question 21

describe a London force

Answer 21

instantaneous dipole in one atom due to the uneven distribution of electrons causes an induced dipole on another atom

Question 22

what is bond length

Answer 22

average distance between 2 nuclei in a covalent bond

Question 23

2 bond pairs no lone pairs

Answer 23

linear 180

Question 24

3 bond pairs no lone pairs

Answer 24

trigonal planar 120

Question 25

4 bond pairs no lone pairs

Answer 25

tetrahedral 109.5

Question 26

5 bond pairs no lone pairs

Answer 26

trigonal bipyramidal 90 120

Question 27

6 bond pairs no lone pairs

Answer 27

octahedral 90

Question 28

2 bond pairs 2 lone pairs

Answer 28

v shaped 104.5

Question 29

3 bond pairs 1 lone pair

Answer 29

trigonal pyramidal 107

Question 30

define electronegativity

Answer 30

the tendency of an element to attract a shared pair of electrons to itself within a covalent bond

Question 31

what makes a polar bond

Answer 31

electronegativity difference between 0.4 and 1.7

Question 32

why might a molecule with polar bonds not be a polar molecule

Answer 32

permanent dipole occurs in a molecule which is asymmetric and has one side which is more positive and one which is more negative, if symmetrical bond is not polar

Question 33

what affects the strength of London forces

Answer 33

greater Mr - stronger London forces straight chain - stronger London forces (less points of contact and reducing distance over which the force acts)

Question 34

what elements can hydrogen bond

Answer 34

oxygen, nitrogen and fluorine (3 most electronegative elements)

Question 35

why does ice have a lower density than water

Answer 35

more space between the molecules in ice as it is a 3d lattice structure, hydrogen bonds are longer than covalent bonds

Question 36

factors affecting strength of metallic bonds

Answer 36

-greater charge on positive ion- stronger attraction as more electrons released into sea -larger ionic radius- weaker attraction

Question 37

bonding and physical properties of metallic compounds

Answer 37

good conductors as delocalised electrons can carry charge malleable as positive ions slide over eachother high melting point solid at room temp

Question 37

bonding and physical properties of simple molecular compounds

Answer 37

low melting and boiling points very poor conductors

Question 38

bonding and physical properties of giant covalent structures

Answer 38

high melting point = multiple covalent bonds

Question 39

diamond properties

Answer 39

each atom bonded to 4 other carbon atoms rigid tetrahedral structure hardest material - why it is used on drills

Question 40

graphite properties

Answer 40

each atom bonded to 3 other carbon atoms in flat hexagonal sheets one delocalised electron per carbon atom - conducts electricity layers slide over eachother due to weak intermolecular forces - lubricant

Question 41

graphene properties

Answer 41

1 layer of graphite - one atom thick hexagonal carbon rings lightweight material

Question 42

why are ionic compounds brittle

Answer 42

when struck with a hammer the layers slide and therefore the positive ions align with positive ions so they repel each other and the compound breaks.

Question 43

what are isoelectric ions

Answer 43

different ions with the same electronic configuration

Question 44

carbon monoxide dot and cross

Answer 44

double bond and dative bond from oxygen to carbon

Question 45

if a bond is shorter does it have a higher/lower bond enthalpy

Answer 45

higher as if there is a greater electron density then the atoms are pulled further towards each other so there is stronger attraction of positive nuclei and negative shared pair of electrons

Question 46

how to answer a shape of molecule question

Answer 46

how many bond pairs + lone pairs it has shape name and bond angles maximum seperation minimum repulsion of electrons

Question 47

what is electrostatic attraction

Answer 47

the attraction between positively-charged and negatively-charged particles

Question 48

what is an ionic lattice

Answer 48

the arrangement of ions into a large structure, consisting of alternating positive ions and negative ions