chem 2

Question 1

which types of elements form covenant bonds

Answer 1

non metals

Question 2

which types of elements form ionic bonds

Answer 2

non metal and non metal

Question 3

what is a covelant bond

Answer 3

chemical bond where two atoms share one or more pairs of electrons to achieve stability

Question 4

why do some structures form giant covalent structures

Answer 4

need for maximum bonding
achieving stability
atoms with high electronegativity and small size

Question 5

why do ionic substances have high melting points ?

Answer 5

strong electrostatic (ionic) bonds and lattice structure that requires a lot of energy to break

Question 6

what element is contained in both diamond and graphite

Answer 6

carbon

Question 7

why does graphite conduct electricity

Answer 7

due to delocalised electrons that can move freely
due to weak van der Waals forces allowing the delocalised electrons to move freely due

Question 8

how many bonds does each carbon atom in a diamond form

Answer 8

4

Question 9

why is graphite slippery and soft

Answer 9

because of its unique layered structure and the weak forces between those layers.

Question 10

what holds metals together

Answer 10

electrostatic attraction, which is the reason metals are so strongly joined

Question 11

what is a polymer

Answer 11

a very long molecule made of many units

Question 12

what is an alloy

Answer 12

an alloy is a mixture of two or more elements, where at least one is a **metal

Question 13

why are alloys harder than pure metals

Answer 13

because they are irregularly arranged which means more energy is needed to separate the bonds as there are no layers

Question 14

what is electrostatic attraction

Answer 14

the force of attraction between opposite electric charges (positive and negative).

Question 15

what is a nanoparticle

Answer 15

a particle with dimensions between 1 and 100 nanometers (nm)

Question 16

what atoms are in simple covalent bonds

Answer 16

non metal

Question 17

what types of atoms are in giant covalent bonds

Answer 17

non metals

Question 18

what types of atoms are in polymer bonds

Answer 18

non metals

Question 19

what are the melting points of simple covalent bonds and why

Answer 19

low MP n BP
weak bonds between them

Question 20

what are the melting points of giant covelant bonds and why

Answer 20

high MP n BP
strong covalent forces between them

Question 21

what are the melting points of polymer bonds and why

Answer 21

low MP n BP
weak intermolecular covalent bonds

Question 22

what are the melting points of metallic bonds and why

Answer 22

moderate to high MP n BP
due to sea of delocalised electrons
positively charged metal ions in lattice structure
more valence electrons

Question 23

what is the state of ionic bonds at room temp

Answer 23

solid

Question 24

what is the state of simple covalent bonds at room temp

Answer 24

gas, occasionally liquid

Question 25

what is the state of giant covalent bonds at room temp

Answer 25

solid

Question 26

what is the state of polymers at room temp

Answer 26

solid

Question 27

what is the state of metallic bonds at room temp

Answer 27

solid

Question 28

what are the two types of polymers

Answer 28

thermosetting and thermosoftening

Question 29

what are the two variables that change a polymer

Answer 29

the monomers it’s made from the conditions the polymer is made in

Question 30

how big is a fine particle

Answer 30

100-2500nm

Question 31

how big is a coarse particle

Answer 31

2500nm-10,000nm

Question 32

what is the use of a nanoparticle

Answer 32

medicine, electronics, cosmetics and sun cream

Question 33

what are risks of nanoparticles

Answer 33

small size may make it possible to breathe in or for them to pass into cells

Question 34

what are coarse particles sometimes referred to as

Answer 34

dust, grit

Question 35

what type of structure is found in diamonds

Answer 35

giant lattice from compression; also has high MP n BP

Question 36

what is an ionic bond

Answer 36

a bond formed with electrostatic attraction between oppositely charged atoms where electrons are transferred

Question 37

what are delocalised electrons

Answer 37

electrons that aren’t in their arranged place

Question 38

why are metals good conductors of thermal energy

Answer 38

due to having delocalised electrons

Question 39

metals are sonorous, what is it?

Answer 39

the ability of a material (typically metals) to produce a **deep, resonant, ringing sound** when struck.

Question 40

metals are ductile, what’s that?

Answer 40

to be able to be stretched thin without breaking

Question 41

what are properties of metals?

Answer 41

mostly soft good conductor of heat and electricity high density typically malleable

Question 42

why can pure metals be shaped easily?

Answer 42

their regular arrangement makes the possibility of layers being blanket slide on top of each other

Question 43

why are pure metals mixed with other metals or elements to make alloys

Answer 43

due to their versatility and harder nature

Question 44

what causes metallic bonding?

Answer 44

when an atom/molecule loses or gains electron(s)

Question 45

list some uses of alloys

Answer 45

pots, pans, automotive, aerospace, construction

Question 46

what’s the composition of bronze

Answer 46

mosyly copper and some tin

Question 47

what’s the composition of brass

Answer 47

mostly copper, some zinc

Question 48

what’s the composition of gold in jewellery

Answer 48

mostly pure gold with alloys

Question 49

what is steel

Answer 49

alloy of carbon and iron

Question 50

properties of high carbon steel

Answer 50

brittle, strong, harder

Question 51

properties of low carbon steel

Answer 51

malleable, lower strength

Question 52

composition of stainless steel

Answer 52

iron, chromium, nickel and other

Question 53

density of aluminium alloys

Answer 53

mostly lightweight

Question 54

why can ionic substances conduct electricity when melted or in water

Answer 54

because the ions are free to move, allowing them to carry an electric current

Question 55

what is the structure of an ionic compound

Answer 55

giant ion lattice

Question 56

examples of covalent bonded substances

Answer 56

H2O, CO2, methane

Question 57

state the name of a covalent bonded substance that is made of very large molecules

Answer 57

polyethene

Question 58

what properties do substances which consist of small molecules usually have

Answer 58

weak intermolecular forces softness solubility

Question 59

How do the intermolecular forces change as the size of the molecule increases?

Answer 59

Forces get stronger

Question 60

how do the melting and boiling points of substances change as the size of the molecule increases?

Answer 60

Melting and boiling points increase

Question 61

describe the physical properties of giant covalent structures

Answer 61

High melting and boiling points, hard, and poor electric conductivity

Question 62

what must happen in giant covalent substances in order for them to melt or boil?

Answer 62

must reach high temp

Question 63

what type of substance are diamond graphite and silicon dioxide examples of

Answer 63

minerals

Question 64

describe the type of particles in covalent substances

Answer 64

molecules

Question 65

why can graphene conduct electricity

Answer 65

it has a hexagonal lattice which allows for the presence of delocalised electrons

Question 66

what is grapheneused for?

Answer 66

electronics

Question 67

what are fullerenes?

Answer 67

a class of carbon allotropes that consist of spherical, ellipsoidal, or cylindrical structures made entirely of carbon

Question 68

what is the fullrene with the formula C60

Answer 68

buckminsterfullrene

Question 69

what shape does a buckminsterfullrene have

Answer 69

football, 20 hexagonal and 12 pentagonal faces

Question 70

describe the forces that are present between the molecules of buckminsterfullerene

Answer 70

van der Walls, intermollecular

Question 71

explain the melting points of Buckminsterfullrene

Answer 71

low due to weak van der Walls, intermolecular forces

Question 72

States one use of fullrenes

Answer 72

drug delivery systems

Question 73

describe the structure of carbon nano tubes

Answer 73

cylindrical and made of rolled up graphene electrons

Question 74

describe the tensile strength of nano tubes

Answer 74

Very high strength

Question 75

and carbon nanotubes conduct electricity

Answer 75

yes, depending on their structure, e.g. metallic or semiconducting

Question 76

describe the structure of graphite

Answer 76

layered two dimensional hexagon lattice

Question 77

describe the strength of the forces in between the layers of graphite

Answer 77

weak van der Walls forces

Question 78

describe the structure of graphene

Answer 78

Single layer of carbon atoms

Question 79

how do strong bonds affect the melting points of graphene

Answer 79

it would raise the melting points and boiling points

Question 80

why can graphite be used as a lubricant

Answer 80

it’s has layers which can easily slide on top of each other alongside intermolecular forces

Question 81

describe the strengths and limitations of a Dot and cross model to show ionic bonding

Answer 81

strength is that it’s clearly shows transfer of electrons limitation is that it’s oversimplifies bonding i’m not showing the true size of the ions

Question 82

describe the strengths and limitations of a ball and stick model to show ionic structure

Answer 82

Clear 3-D representation of ionic structure however may not represents real relative size

Question 83

describe the strengths and weaknesses of a 3-D diagram of an ionic lattice to show ionic structures

Answer 83

realistic view of arrangements complex and hard to interpret for people that are unexperienced

Question 84

describe the strengths and weaknesses of a 2-D diagram of an ionic lattice to show ionic structures

Answer 84

simplify the representation for easy interpretation does not show 3-D nature of structure

Question 85

What does nano science refer to?

Answer 85

The study of structures and materials between 1 to 100 nm

Question 86

what’s a nano tubes used for?

Answer 86

electronics and medicine

Question 87

why are smaller quantities of nano particles as effective as a larger quantities of materials with larger particles sizes?

Answer 87

higher reactivity and targeted delivery

Question 88

Why do nano particles have different properties from the same materials in bulk?

Answer 88

Surface area to volume ratio increases dramatically

Question 89

what is the monomer that makes up both low density polyethene and high density polyethene

Answer 89

ethylene

Question 90

why are polymers generally solids at room temperature?

Answer 90

van der walls forces