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 positive 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

what is bond angle

Answer 23

angle between two covalent bonds from the same atom

Question 24

2 bond pairs no lone pairs

Answer 24

linear 180

Question 25

3 bond pairs no lone pairs

Answer 25

trigonal planar 120

Question 26

4 bond pairs no lone pairs

Answer 26

tetrahedral 109.5

Question 27

5 bond pairs no lone pairs

Answer 27

trigonal bipyramidal 90 120

Question 28

6 bond pairs no lone pairs

Answer 28

octahedral 90

Question 29

2 bond pairs 2 lone pairs

Answer 29

v shaped 104.5

Question 30

3 bond pairs 1 lone pair

Answer 30

trigonal pyramidal 107

Question 31

define electronegativity

Answer 31

the power of an atom to attract the electron pair in a covalent bond towards itself

Question 32

what makes a polar bond

Answer 32

electronegativity difference between 0.4 and 1.7

Question 33

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

Answer 33

carbon dioxide is linear so the dipoles cancel out on the C and O

Question 34

what affects the strength of London forces

Answer 34

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

Question 35

what elements can hydrogen bond

Answer 35

oxygen, nitrogen and fluorine (3 most electronegative elements)

Question 36

why does ice have a lower density than water

Answer 36

hydrogen bonds hold the molecules in a rigid structure with lots of air gaps whereas in water the bonds constantly break and reform so molecules are closer together

Question 37

describe trend in hydrogen halide boiling points

Answer 37

HF - hydrogen bonds so highest

increases as you go down group as ionic radius of halide increases so it has more electrons so stronger London forces

Question 38

factors affecting strength of metallic bonds

Answer 38

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

Question 39

bonding and physical properties of ionic crystal lattice

Answer 39

high melting and boiling point
when molten or in solution they can conduct electricity as ions can carry charge and are free to move
brittle

Question 40

bonding and physical properties of metallic compounds

Answer 40

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

Question 40

bonding and physical properties of simple molecular compounds

Answer 40

low melting and boiling points
very poor conductors

Question 41

bonding and physical properties of giant covalent structures

Answer 41

high melting point = multiple covalent bonds

Question 42

diamond properties

Answer 42

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

Question 43

graphite properties

Answer 43

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 44

graphene properties

Answer 44

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