bonding and structure

Question 1

ionic bond

Answer 1

the attraction between oppositely charged ions

Question 2

structure of an ionic compound

Answer 2

ionic lattice

Question 3

properties of ionic compounds

Answer 3

1. high melting and boiling points- strong ionic bonds that require a lot of energy to break
2. cannot conduct electricity when solid, only when liquid- when solid, ions are not free to move and carry charge
   when liquid, ions are free to move and carry charge

Question 4

ionic bonding occurs between __________________________________

Answer 4

a metal and non-metal

Question 5

how is an ionic bond formed

Answer 5

electrons are transfered from the metal to non-metal

Question 6

definition of a covalent bond

Answer 6

a shared pair of electrons

Question 7

definition of a molecule

Answer 7

2 or more atoms covalently bonded together

Question 8

definition of diatomic

Answer 8

2 atoms covelantly bonded in a molecule

Question 9

what types of elements are present in substances which contain covalent bonds

Answer 9

non-metals

Question 10

2 types of covelant bonds

Answer 10

simple and giant

Question 11

why do simple covelant substances have low melting and boiling points

Answer 11

have weak van der waals’ forces between the molecules which require little energy to break

Question 12

why are simple covelant substances poor conductors of electricity

Answer 12

thye do not have delocalised electrons that can move and carry charge

Question 13

properties of simple covelant substances

Answer 13

1. low melting and boiling points
2. they are soft and brittle
3. poor conductors of electricity
4. insoluble in water

Question 14

examples of giant covelant structures

Answer 14

graphite
graphene (one layer of graphite)
diamond

Question 15

why do giant covalent structures have hight melting and boiling points

Answer 15

have strong covelant bonds which require lots of energy to break

Question 16

definition of an allotrope

Answer 16

different forms of the same element in the same state

Question 17

in diamond each carbon atom is bonded to _____1._ other carbon atoms to form a _____2._____ structure

Answer 17

1. 4
2. tetrahedral

Question 18

state the properties of diamond

Answer 18

1. high melting and boiling points
2. poor conductors of electricity
3. hard

Question 19

state the properties of graphite

Answer 19

1. high melting and boiling points
2. good conductors of electricity
3. soft

Question 20

state the properties of graphene

Answer 20

1. high melting and boiling points
2. good conductors of electricity
3. hard

Question 21

definition of a metallic bond

Answer 21

the attraction between delocalised electrons and a regular lattic of positive ions

Question 22

properties of metals

Answer 22

1. metals often have high melting and boiling points
2. metals are good conductors of electricity
3. metals are malleable and ductile

Question 23

definition of malleable

Answer 23

can be hammared into shape

Question 24

definition of ductile

Answer 24

can be drawn into a wire

Question 25

why do metals usually have high melting and boiling points

Answer 25

metallic bond is strong and requires a lot of energy to break

Question 26

why are metals good conductors of electricity

Answer 26

the electrons are delocalised and are free to move and carry the charge

Question 27

why are metals malleable and ductile

Answer 27

layers (of ions) can slide over each other without disrupting the structure

Question 28

definition of an alloy

Answer 28

a mixture of elements, at least one of which is a metal

Question 29

why are alloys harder than pure metals

Answer 29

some of the ions (or atoms) in the alloy of a different size to those of the metal. this distorts the layers and makes it more difficult for the layers to slide over each other

Question 30

equation to determine the % of gold in an alloy

Answer 30

number of carats/24 x 100

Question 31

state a use of aluminium

Answer 31

overhead electrical wiring, alloys for aircraft

Question 32

state a use of copper

Answer 32

electrical wiring, plumbing, brass, coinage

Question 33

state a use of iron

Answer 33

bridges

Question 34

state a use of magnesium

Answer 34

flares, high strength, low density alloys for aircraft

Question 35

what is a nanoparticle

Answer 35

a structure that is 1-100nm in size and contains a few hundred atoms

Question 36

why do nanoparticles have different properties and uses than the bulk material

Answer 36

high surface area to volume ratio

Question 37

state a use of nanoparticles in sun cream

Answer 37

better skin coverage to the sun cream, more effective protection from u.v. rays, invisible on the skin, do not degrade on exposure to the sun

Question 38

what are the potential risks of using nanoparticles

Answer 38

cell damage, harmful effects on the enviroment