structure and bonding

Question 1

ionic structure =

Answer 1

ionic structure = giant ionic lattice

Question 2

properties of ionic substancesand why

Answer 2

high melting + boiling points - a lot of energy is needed to overcome the strong electrostatic force of attraction between oppositely charged ions
most are soluble in water
non conductor as a solid - ions held in fixed positions so cannot move and carry a charge
solutions and molten ionic substances are conductors - the ionic lattice breaks down so the ions are free to move and carry a charge + energy

Question 3

covalent bonding definition

Answer 3

sharing of pairs of outer shell electrons between non metal atoms

Question 4

most covalent substances exist as..

Answer 4

simple covalent molecule

Question 5

properties of covalent substances

Answer 5

low melting + boiling point - not a lot of energy is needed to overcome the weak intermolecular forces between simple covalent molecules
non conductors of electricity - there is no overall charge on molecules and there are no charged particles that can move

Question 6

some covalent structures exist as what and give examples

Answer 6

some covalent structures exist as giant covalent structures e.g. diamond. graphite.silica (silicon dioxide)

Question 7

structure of diamond

Answer 7

each carbon atom is bonded via 4 strong covalent bonds to 4 other carbon atom

Question 8

properties of diamond

Answer 8

very hard - strong covalent bonds to each carbon
very high melting point - a lot of energy is needed to break strong covalent bond
non conductor - no overall charge/no charged particles free to move

Question 9

structure of graphite

Answer 9

each carbon forms 3 strong covalent bonds with a delocalised electron from each carbon between the layers. it has layers of hexagonal rings of carbon with weak forces between the layers

Question 10

graphite properties

Answer 10

conductor - delocalised electrons free to move between layers
soft - layers can slide due to weak forces
high melting point - a lot of energy is needed to break the many strong covalent bonds

Question 11

allotrope definition

Answer 11

different forms of the same element which exist at the same temp and pressure

Question 12

name 5 carbon allotropes

Answer 12

graphite,diamond and graphene,fullerenes.carbon nanotubes

Question 13

fullerenes are what and using in…

Answer 13

fullurenes are simple molecules used in lubricants and electronics

Question 14

structure of fullurenes

Answer 14

hollow,spherical,hexagonal/pentagonal rings of carbon

Question 15

what was the first fullerene to be discovered

Answer 15

buckminster fullerene ( 60 carbon nanotubes)

Question 16

carbon nanotubes are..

Answer 16

carbon nanotubes are cylandrical fullerenes with a high length to diameter ratio

Question 17

properties of metals and why

Answer 17

electrical conductor - delocalised electrons free to move and carry a charge
high melting point - a lot of energy is needed to overcome the strong electrostatic force of attraction between positive meal ions and a sea of delocalised electrons
ductile/malleable/soft - positive metal ions are arranged in neat rows that can slide past each other whilst remaining bonded
heat/thermal conductor - energy is transferred by the delocalised electrons moving through the structure
high density - have a highly packed lattice structure ( large mass to volume ratio)

Question 18

alloys are a mixture of what

Answer 18

alloys are a mixture of 2 or more elements where at least one of which is a metal

Question 19

alkenes are

Answer 19

alkenes are simple covalent molecules

Question 20

when are polymers formed

Answer 20

polymers are formed when small molecules (monomers) join together to form long chains (polymers) this is called polymerisation

Question 21

polymers are..

Answer 21

polyers are very large simple covalent molecules

Question 22

monomer -> polymer
ethene ->
vinylchloride _>
vinylacetate ->

Answer 22

ethene -> polyethene
vinylchloride -> polyvinylchloride
vinylacetate -> polyvinylacetate

Question 23

polymers are what at room temp

Answer 23

polymers are solid at room temp despite being simple covalent molecules

Question 24

why do polymers have high melting point

Answer 24

they have high melting point because they are large molecules so more energy is needed to overcome the many weak intermolecular forces between polymer chainsw

Question 25

why do polymers tend to stretch rather than snap

Answer 25

they tend to stretch because the long chains can slide over one another

Question 26

dust is a what particle which has a size of…

Answer 26

dust is a coarse particle (PM10) which has a size of 10,000 - 25,000nm

Question 27

fine particles (PM2.5) have a size of

Answer 27

100-2500nm

Question 28

are nanoparticles or atoms larger?

Answer 28

nanoparticles are larger than atoms because they’re made up of a few hundred atoms

Question 29

as a material is divided into smaller and smaller particles the what increases

Answer 29

as a material is divided into smaller and smaller particles,the overall surface area increases

Question 30

nanoparticles have a very high surface area to volume ratio compared to the same material in bulk name the uses

Answer 30

uses:
medicines.electronics.catalysts,cosmetics e.g. sunscreen
risks:
explosions, absorption through skin and in blood, lung damage