topic two Flashcards by rachel dhad

describe the structure of metals?

giant structure
metal ions in layers
delocalised electrons

How well did you know this?

Not at all

Perfectly

explain why polymers have higher melting points relative to substances made of small molecules?

they have much larger molecules
so stronger intermolecular forces
which require more energy to overcome

How well did you know this?

Not at all

Perfectly

give two typical properties of substances made of small molecules?

low melting and boiling points
do not conduct electricity

How well did you know this?

Not at all

Perfectly

explain why diamond is hard?

it has a giant covalent structure
it has strong covalent bonds between atoms
which are hard to break

How well did you know this?

Not at all

Perfectly

explain why larger molecules have higher melting and boiling points than smaller ones?

they have stronger intermolecular forces
which require more energy to overcome

How well did you know this?

Not at all

Perfectly

describe what happens to electrons in ionic bonding?

they are transferred from one atom to another

How well did you know this?

Not at all

Perfectly

describe the structure of graphene?

one layer of graphite

How well did you know this?

Not at all

Perfectly

explain how graphite conducts electricity, reference its structure and bonding?

each carbon atom has three bonds only
there is therefore one delocalised electron per carbon atom
the delocalised electrons are free to carry charge through the graphite

How well did you know this?

Not at all

Perfectly

three main types of substances formed from covalently bonded atoms?

small molecules
very large molecules
and giant covalent structures

How well did you know this?

Not at all

Perfectly

explain why ionic substances do not conduct electricity when solid?

because the ions are not free to move, so charge cannot flow

How well did you know this?

Not at all

Perfectly

typical properties of pure metals?

high melting and boiling points
malleable
good conductors of electricity
good conductors of thermal energy

How well did you know this?

Not at all

Perfectly

describe the structure of substances consisting of small molecules?

small molecules made up of atoms held together by strong covalent bonds
weak intermolecular forces act between the molecules

How well did you know this?

Not at all

Perfectly

explain why ionic substances have high melting points?

there is a strong electrostatic force of attraction between oppositely charged ions which requires a lot of energy to break

How well did you know this?

Not at all

Perfectly

explain why non metals do not form ionic bonds with each other?

non metal ions form negative charges, so would repel

How well did you know this?

Not at all

Perfectly

explain why metals are good conductors of thermal energy?

delocalised electrons can move through the metal and transfer energy

How well did you know this?

Not at all

Perfectly

two limitations of dot and cross diagram for ionic bonding?

it has only two ions and therefore does not show the giant structure

it does not show the three dimensional nature of the structure

How well did you know this?

Not at all

Perfectly

3 examples of substances that consist of small molecules?

oxygen, water, ammonia

How well did you know this?

Not at all

Perfectly

structure formed when metals and non metals react?

giant ionic structure

How well did you know this?

Not at all

Perfectly

two properties of ionic susbtances?

high melting and boiling points
only conduct electricity when molten or in solution

How well did you know this?

Not at all

Perfectly

explain why graphite can act as a lubricant?

there are no covalent bonds between the layers
so they are free to slide over each other

How well did you know this?

Not at all

Perfectly

describe structure of a giant ionic lattice?

a 3d network of alternating positive and negative ions held together by the electrostatic force of attraction

How well did you know this?

Not at all

Perfectly

how many bonds does each carbon atom have in diamond?

four

How well did you know this?

Not at all

Perfectly

explain why buckminsterfullerene can be used as a lubricant?

the molecules have a spherical shape so can roll over each other

How well did you know this?

Not at all

Perfectly

two limitations of ionic bonding structure diagram? NOT BALL AND STICK

ions do not actually touch
does not show electrons

How well did you know this?

Not at all

Perfectly

3 properties of graphene?

high melting point strong conducts electricity

explain why diamond does not conduct electricity?

the atoms do not have an overall charge it does not have delocalised electrons so charge cannot flow

structure of typical alloy?

metallic structure with atoms of different metals or carbon mixed in

3 examples of substances with a giant covalent structure?

diamond, silicon dioxide and graphite

explain why ionic substances conduct electricity in solution?

because the ions are free to move, SO CHARGE CAN FLOW

explain why simple molecular substances have low melting points?

weak intermolecular forces require little energy to overcome

explain in terms of electrons what occurs when magnesium reacts with oxygen to form magnesium oxide?

2 electrons are transferred from a magnesium atom to an oxygen atom the ions have full outer shells the ions are then attracted to each other by the electrostatic force of attraction

three uses of nanotubes?

nanotechnology electronics materials

relationship between size of a molecules and strength of its intermolecular forces?

larger a molecule, stronger its intermolecular forces

explain in terms of electrons what occurs when lithium reacts with oxygen to form lithium oxide?

2 lithium atoms transfer one electron each to one atom of oxygen the ions have full outer shells the ions are then attracted to each other by the electrostatic force of attraction

explain why substances consisting of small molecules do not conduct electricity?

the molecules do not have an overall electric charge so charge cannot flow

describe the structure of graphite?

each carbon atom forms three covalent bonds with three other carbon atoms the atoms form layers made of hexagonal rings

name three properties of diamond?

high melting and boiling points does not conduct electricity very hard

give two uses of graphene?

electronics and composites

explain in terms of electrons what occurs when magnesium reacts with chlorine to form magnesium chloride?

one magnesium atom transfers one electron to one chlorine atom, and another electron to a second chlorine atom. the ions have full outer shells the ions are then attracted to each other by the electrostatic force of attraction

explain why alloys can be harder than pure metals?

they have atoms of different sizes which distort the layers of the structure and prevent them from sliding over each other easily

explain why ionic substances conduct electricity when molten?

because ions are free to move and carry charge

explain why pure metals have high melting and boiling points?

strong metallic bonds between metal ions are delocalised electrons require a lot of energy to overcome

when a substance consisting of small molecules is melted or boiled, identify the forces that are overcome?

intermolecular forces NOT COVALENT BONDS

explain why diamond has a high melting and boiling point?

it has a giant covalent structure it has strong covalent bonds between atoms which require a lot of energy to overcome

explain why metals are good conductors of electricity?

delocalised electrons can move through the metal and carry charge

group 8 forms ion, charge?

structure that is made of billions of atoms covalently bonded together?

giant covalent structure

typical state that substances made of small molecules are at room temp?

liquid or gas

explain why pure metals are malleable?

layers of metal ions are free to slide over each other

structural features that gives nanotubes their special properties?

a high length to diameter ratio

group 7 forms ion, state charge?

structure of fullerenes?

molecules made of rings of carbon atoms with hollow shapes

two limitations of ball and stick for ionic bonding?

chemical bonds are not physical things like sticks it does not show electrons

structure of nanotubes?

cylindrical fullerenes

4 uses of nanoparticles?

nanomedicine nanoparticles in electrical circuits silver nanoparticles for antibacterial properties catalysts

how are nanoparticles used in nanomedicine?

fullerenes deliver drugs directly to the insider of cells, so tiny

how are nanoparticles used in electrical circuits?

some of them conduct electricity, so can theoretically make tiny computer chips

how are nanoparticles used in silver nanoparticles for antibacterial properties?

infuse them into surgical masks, wound dressings like plasters to kill bacteria

how are nanoparticles used in catalysts?

exposed SA is important, need much less nanoparticles in materials than bigger particles

evaluate the use of nanoparticles in suncream?

- YES more effective at protecting out skin from harmful UV rays because they provide better skin coverage - NO not clear if nanoparticles can get into out bodies, and whether they could be damaging our cells if they do - NO don't know what happens to them once washed into sea- possible they could be damaging the environment