2-bonding structure and properties of matter

Question 1

how are ions formed when electrons are transferred

Answer 1

when atoms lose or gain electrons to form ions, theyre trying to get a full outer shell like a noble gas (stable electronic structure) as atoms with full outer shells are stable
when metals form ions they lose electrons from their outer shell to form positive ions
when non metals form ions they gain electrons into their outer shell to form negative ions
the number of electrons lost or gained is the same as the charge of the ions
(if 2 electrons are lost = 2+)
(if 2 electrons gained = 2-)

Question 2

what is an ion

Answer 2

a charged particle
they can be single atoms like Cl-
or a group of atoms NO3-

Question 3

why are group 1 and 2
and group 6 and 7
most likely to form ions

Answer 3

g1 and g2 are metals and they lose electrons to form positive iosn (cations)

g6 and g7 are non metals that gain electrons to form negative iosn (anions)

group 1 form 1+ ions
group 2 forms 2+ ions
group 6 forms 2- ions
group 7 forms 1- ions

Question 3

why are group 1 and 2
and group 6 and 7
most likely to form ions

Answer 3

g1 and g2 are metals and they lose electrons to form positive iosn (cations)

g6 and g7 are non metals that gain electrons to form negative iosn (anions)

group 1 form 1+ ions
group 2 forms 2+ ions
group 6 forms 2- ions
group 7 forms 1- ions

Question 4

show the ionisation equations for
sodium
magnesium
chlorine
oxygen

Answer 4

1-sodium: loses 1 electron to form sodium ion with same electronic structure as neon
Na => Na+ +e-

2=magnesium: loses 2 electrons to form a magnesiumion with same electronic structure as neon
Mg => Mg2+ + 2e-

3= chlorine: gains 1 electron to form a chloride ion with same electronic structure as argon
Cl + e- => Cl-

4= oxygen: gains 2 electrons to form an oxide ion with same electronic structure as neon
O + 2e- => O2-

Question 5

what is ionic bonding

Answer 5

when a metal and a non metal react together
the metal atom loses electrons to form a positively charged ion and the nonmetal gains these electrons to form a negatively charged ion
these oppositely charged ions are strongly attracted to one another by electrostatic forces
this attraction is called an ionic bond

Question 6

what do dot and cross diagrams show

Answer 6

it shows the arrangement of electrons in an atom or ion
each electron is represented by a dot or cross
so these diagrams show which atom the electrons in an ion originally came from
they show how the ionic compound is formed but dont show the structure of the compound, thesize of the ions or how theyre arranged

Question 7

what kind of structure do ionic compounds form

Answer 7

giant ionic lattice
ions form a closely packed regular lattice arrangment, theres strong electrostatic forces between oppositely charged ions in all directions in the lattice
e.g. a single crystal of sodium chloride(table salt ) is one giant ionic lattice. the Na+ & Cl- ions are held together in a regular lattice

Question 8

how can giant ionic lattices be shown through diagrams
describe the 2 ways

Answer 8

1)model = shows relative size of ions,shows regular pattrn of ionic crystal but only shows outer layer of compound

2) ball and stick model shows regular pattern of an ionic crystal, shows how all ions are arranged, it suggests that the crystals extends beyond whats shown in the diagram
but model isnt to scale so relative sizes of ions may not be shown and in reality there are not gaps between the ions e.g. in Na+ and Cl- ions are alternate

Question 9

what are all the similar properties of ionic compounds

Answer 9

high melting and boiling point due to many strong bonds between the ions, takes a lot if energy to overcome this attraction
when solid, the ions are held in place so compounds cant conduct electricity, when ionic compounds melt,ions are free to move so theyll carry electric current
some ionic compounds also dissolve in water, ions separate are all free to move in solution so theyll carry electric current

Question 10

How to find empirical formula of an ionic compound

Answer 10

from the diagram of a compound

if its dot&cross= count up how many atoms there are of each element to get empirical formula
if you have 3d diagram of ionic lattice, use it to work out what ions are in the ionic compound
then balance charges of the ions so that overall chargge on compound is 0

e.g. a compound with potassium and oxide ions
potassium is g1 so 1+ ions
oxygen is g6 so 2- ions
potassium ion only has a 1+ charge sp you need 2 of them to balance out 2- charge of oxideion so K2O

Question 11

explain how covalent bonding works

Answer 11

when nonmetals atoms bond together they share pairs of electrons to make covalent bonds
positively charged nuclei of bonded atoms are attracted to the shared pair of electrons by electrostatc forces making covalent bonds very strong
atoms only share electrons in their outer shells(energy level)
each single covalent bond provides one extra shared electron for each atom
each atom involved generally makes enough covalent bonds to fill up its outer shell. full outer shell gives them the electronic structure of a noble gas=stable
covalent bonding happens in compounds of non metals (H2O) and in non metal elements (Cl2)

Question 12

how can you show covalent bonding with dot and cross diagram

Answer 12

dot and cross diagram =overlap between outer orbitals of 2 atoms are shared between those atoms
they are useful for showing which atoms the electrons in a covalent bond come from
but they dont show the relative sizes of the atoms or how the atoms are arranged in space

Question 13

vhow can you show covalent bonding with the displayed formula

Answer 13

shows covalent bonds as single lines between atoms
its good for showing how atoms are connected in large molecules
but they dont show 3D structure of molecule or which atoms the electrons in the covalent bond have come from

Question 14

how can you show covalent bonding with 3D model

Answer 14

it shows atoms, covalent bonds, arrangement in space next to each other
but 3D models can quickly get confusing for large molecules where there are lots of atoms to include
they dont show where the electrons in the bonds have come from either

Question 15

how can you find the molecular formula of a simple molecular compound from any of the 3 diagrams

Answer 15

count up how many atoms of each element there are
H H
| |
e.g. H -C-C- H
| |
H H
so it is C2H6

Question 16

what are simple molecular substances and give examples

Answer 16

they are made up of molecules containing a few atoms joined together by covalent bonds

hydrogen - H2
has 1 electron to complete 1st shell so they form single covalent bonds with hydrogen atoms or with other elements

oxygen- O2
each oxygen atom needs 2 more electrons to complete its outer shell so in oxygen gas, 2 oxygen atoms share 2 pairs of electrons with each other making a double covalent bond

methane CH4
carbon has 4 outer electrons which is half a full shell
forms 4 covalent bonds with hydrogen atoms to fill outer shell

chlorine Cl2
each atom needs 1 more electron to complete outer shell so 2 chlroine atoms can hare 1 pair of electrons and form a single covalentbond

nitrogen N2
they need 3 more electron so 2 nitrogen atoms share 3 pairs of electrons to fill their outer shells to make triple bond

water H2O
water molecules, oxygen shares a pair of electrons with 2 H atoms to form 2 single covalent bonds

hydrogen chloride HCl
both atoms need one more electron to complete their outer shells

Question 17

what are properties of simple molecular substances substances containing covalent bonds

Answer 17

1- atoms held together by strong covalent bonds but forces of attraction between molecules are very weak
2-to melt or boil a simple molecular compound you only need to break feeble intermolecular forces and not covalent bonds so melting and boiling point is very low because molecules are easily parted from each other
3-most are gases or liquids at room temp
4- as molecules get bigger, strength of intermolecular forces increase so more energy needed to break them and melting and boiling point increases
5-molecular compounds dont conduct electricity bc they are not charged so no free electrons or ions

Question 18

what are polymers

Answer 18

lots of small units linked together to form a long molecule that has repeating sections
all the atoms in a polymer are joined by strong covalent bonds

Question 19

how do you show polymers through diagram

Answer 19

draw the shortest repeating section called repeating unit
the part in the bracket is the repeating unit
‘n’ is the large number tell you the unit has repeated lots of times
bonds through the brackets join up to the next repeating unit

Question 20

explain how intermolecular forces work in polymer molecules

Answer 20

they are larger than the ones in simple covalent molecules so more energy is needed to break them so most polymers are solid at room temperature
intermolecular forces are still weaker than ionic or covalent bonds so they generally have lower boiling points than ionic and giant molecular compounds

Question 21

why are giant covalent structures macromolecules

Answer 21

all atoms are bonded to each other by strong covalent bonds
high melting and boiling point as lots of energy is needed to break the covalent bonds between atoms
dont contain charged particles so dont conduct electricity not even when molten (except for things like graphite)
main examples are diamond and graphite both made from carbon atoms only and silicon dioxide

Question 21

why are giant covalent structures macromolecules

Answer 21

all atoms are bonded to each other by strong covalent bonds
high melting and boiling point as lots of energy is needed to break the covalent bonds between atoms
dont contain charged particles so dont conduct electricity not even when molten (except for things like graphite)
main examples are diamond and graphite both made from carbon atoms only and silicon dioxide

Question 22

explain how diamonds are structured

Answer 22

each carbon atom forms 4 covalent bonds in a very rigid giant covalent structure

Question 23

explain how graphite is structured

Answer 23

each carbon atom forms 3 covalent bonds to create layers of hexagons each carbon atom also has 1 delocalised free electron

Question 24

explain how silicon dioxide is structured

Answer 24

sometimes called silica what sand is made from each grain of sand is 1 giant structure of silicon and oxygen

Question 25

explain properties of diamond

Answer 25

giant covalent structure made up of carbon atoms that each form 4 covalent bonds making diamond rlly hard strong covalent bonds take a lot of energy to break so it has a high melting point doesnt conduct electricity bc it has no free electrons or ions

Question 26

explain properties of graphite

Answer 26

each carbon atom forms 3 covalent bonds creating sheets of carbon atoms arranged in hexagons arent any covalent bonds between the layer, only held together weakly so theyre free to move over each other it is soft and slippery so ideal for lubricating material high melting point bc covalent bonds in layers need loads of energy to break only 3 out of each carbon''s 4 outer ekectrons are used in bonds so each carbon atom has 1 electron that is delocalised, free to move so it can conduct electricity and thermal energy

Question 27

explain graphene

Answer 27

graphene is one layer of graphite its a sheet of carbon atoms joined togehter in hexagons sheet is 1 atom thick making it a 2d compound network of covalent bonds makes it very strong it is incredibly light so can be added to composite materials to improve their strength without adding much weight like graphite, it contains delocalised electrons so can conduct electricity through whole structure, so it can be used in electronics

Question 28

what are fullerenes

Answer 28

are molecules of carbon shaped like closed tubes or hollow balls

Question 29

what is buckministerfullerene

Answer 29

first fullerene to be discovered molecular formula is C60 and forms a hollow sphere

Question 30

what are fullerenes made up of what can they be used for

Answer 30

made up of carbon atoms arranged in hexagons can also contain pentagons(rings of 5 carbon atoms) or heptagons (rings of 7 carbon atoms) they have a huge surface area so they make good industrial catalysts (individual catalyst molecules could be attached to the fullerenes, fullerenes also make great lubricants) they can be used to cage other molecules fullerene structure forms around another atom or molecule which is then trapped inside (could be used to deliver a drug into the body)

Question 31

what are nanotubes and how do fullerens form them

Answer 31

fullerenes can form nanotubes which are tiny carbon cylinders ratio betwee length and diameter of nanotubes are very high nanotubes can conduct both electric and thermal energy(heat) also has high tensile strength (dont break when stretched) technology using small particles such as nanotubes is called nanotechnology nanotubes can be used in electronics or to strengthen materials without adding much weight e.g. tennis racket frame

Question 32

explain how metallic bonding works

Answer 32

metals also consist of a giant structure electrons in the outer shell of the metal atoms are delocalised (free to move) there are strong forces of electrostatic attraction between the positive metal ions and the shared negative electrons these forces of attraction hold the atoms together in a regular structure =metallic bonding it is very strong substances held together by metallic bonding = metallic elements and alloys its delocalised electrons in the metallic bonds produce all properties of metals

Question 33

why are metals solid at room temperature

Answer 33

electrostatic forces between metal atoms and delocalised sea of electrons are strong so needs lots of energy to be broken the most compounds with metallic bonds have very high melting and boiling points so theyre generally solid at room temp

Question 34

why are metals good conductors of electricity and heat

Answer 34

delocalised electrons carry electrical current and thermal heat energy through the whole structure so metals are good conductors of heat and electricity

Question 34

why are metals good conductors of electricity and heat

Answer 34

delocalised electrons carry electrical current and thermal heat energy through the whole structure so metals are good conductors of heat and electricity

Question 35

why are most metals malleable

Answer 35

layers of atoms in a metal can slide over each other making metals malleable so they can be bent or hammered or rolled into flat sheets

Question 36

why are alloys harder than pure metals

Answer 36

pure metals often arent right for certain jobs, too soft when theyre pure so theyre mixed with other metals to make them harder most of the metals used everyday are alloys = a mixture of 2 or more metals or a metal and another element, alloys are harder so theyre more useful than pure metals different elements have different sized atoms, so when another element is mixed with a pure metal, the new metal atoms will distort the layers of the metal atoms making it more difficult for them to slide over each other, this makes alloys harder than oure metals

Question 37

what does the state of something depend on

Answer 37

how strong the forces attraction are between the particles of the material which depends on material(structure of substance, type of bonds holding it together) temperature pressure

Question 38

explain arrangement of solids

Answer 38

strong forces of attraction between particles which holds them close together in fixed positions to form regular lattice arrangement particles dont more from their positions so all solids keep definite shape and volume particles viibrate in fixed position hotter the solid becomes the more they vibrate (causing solids to expand slightly when heated)

Question 39

explain arrangement of solids

Answer 39

strong forces of attraction between particles which holds them close together in fixed positions to form regular lattice arrangement particles dont more from their positions so all solids keep definite shape and volume particles viibrate in fixed position hotter the solid becomes the more they vibrate (causing solids to expand slightly when heated)

Question 40

explain arrangement of liquids

Answer 40

weak force of attraction between particles randomly arranged and free to move past each other but tend to stick closely togehter has definite volume doesnt have definite shape but will flow to fill bottom of a container particles constantly moving with random motion hotter the liquid, faster it moves causes liquids to expand slightly when heated

Question 41

explain arrangement of gas

Answer 41

forces of attraction between particles is veryweak theyre free to move and are far apart particles in gases travel in straight lines they dont keep definite shape/volume and will always fill any container particles constantly move with random motion the hotter the gas gets, the faster they move gases expand when heated or pressure increases

Question 42

advantages and disadvantages of particle theory

Answer 42

great model for explaining the 3 states of matteer but particles arent solid or inelastic and they arent spheres theyre atoms,ions or molecules model doesnt show forces between the particles so theres no way in showing how strong they are

Question 43

what are the state symbols for solids liquid gas aqueous

Answer 43

solid is s liquid is l gas is g aqueous is aq

Question 44

explain the change in particle arrangement when solid melts to become liquid

Answer 44

when solid is heated particles gain more energy particles vibrate more which weakens forces holding solid together at a certain temperature (melting point) particles have enough energy to break free from positions this is melting aand solid becomes liquid

Question 45

explain boiling/evaporating from liquid to gas

Answer 45

when a liquid is heated again,the particles get even more energy energy makes particles move faster which weakens and breaks bonds holding the liquid together at a certain temp(boiling point) particles have enough energy to break bonds =this is boiling/evaporating liquid becomes a gas

Question 46

explain condensation from a gas to a liquid

Answer 46

as gas cools particles no longer have enough energy to overcome the forces of attraction between them bonds then form between the particles at the boiling point so many bonds have formed between gas particles that the gas has become a liquid= condensing

Question 47

explain freezing from a liquid to a gas

Answer 47

when a lquid cools, the particles have less energy so moves around less theres not enough energy to overcome the attraction between the particles so more bonds form between them at the melting point so many bonds have formed between the particles that theyre held in place so the liquid becomes a solid this is freezing

Question 48

what does the amount of energy needed for a substance to change state depend on

Answer 48

how strong the forces between the particles are the stronger the forces= the more energy is needed to break them so the higher the melting and boiling point is of the substance

Question 49

how can predict the state of a substance at a certain substance

Answer 49

if temp is below the melting point of a substance it will be a solid if its above the boiling point it will be a gas if its between 2 points,its a liquid

Question 50

what categories are particles put into depending on size of their diameter

Answer 50

coarse particles fine particles nanoparticles

Question 51

explain coarse particles

Answer 51

PM10 diameter is between 2500 nm (2.5 x 10^-6) and 10 000 nm (1x10^-5m) it is also called dust

Question 52

explain fine particles

Answer 52

PM2.5 diameter between 100nm (1x10^-7) and 2500nm (2.5x10^-6m)

Question 53

explain nano particles

Answer 53

diameter is between 1nm (1 x 10^-9 m) and 100nm(1x10^-7m) these are particles that contain only a few hundred atoms there is a whole area of science investigating uses and propeties of nanoparticles called nanoscience nanoparticles have a large surface area to volume ratio, surface area is very large compared to volume

Question 54

explain how to calculate surface area to volume ratio

Answer 54

surface area / volume total surface area= x surface area by number of faces as particles decrease in size,the size of their surface area increases in relation to their volume causing the surface area to volume ratio to increase as you decrease the side of any cube by a factor of 10, the surface area to volume ratio will always increase by a factor of 10

Question 55

what does it mean if nanoparticles have a high surface area to volume ratio

Answer 55

surface area is large compared to the volume this can cause the properties of a material to be different depending on whether its a nanoparticle or whether its in bulk e.g youll often need less of a material that is made up of nanoparticles to work as an effective catalyst compared to a material made up of normal sized particles containing billions of atoms rathher than a few hundred

Question 56

what can nanoparticles be used for

Answer 56

1-huge surface area to volume ratio so they can help make new catalysts 2-nanomedicine, tiny particles (e.g. fullerenes) are absorbed more easily by the body than most particles this means they could deliver drugs right into the cells where theyre needed 3- nanoparticles can conduct electricity so can be used in tiny electric circuits for computer chips 4- silver nanoparticles have antibacterial properties #, can be added to polymer fibres used to make surgical masks and wound dressings, can also be used in deodorants 5- used in cosmetics e.g. used to improve moisturisers without making them really oily

Question 57

issues involved with nanoparticles being in products

Answer 57

the way nanoparticles affect the body is not fully understood so its important that new products are tested thoroughly to minimise the risks -products with nanoparticles have been available before effects on human health have been investigated properly so we dont know what long term impacts on health will be -as long as long term impacts are not known, many believe products containing nanoscale particles should be clearly labelled so consumers can choose whether or not to use them

Question 58

why are nanoparticles used in sun creams what are issues with this

Answer 58

they have been shown to be better than the materials in traditional in sun creams at protecting skin from harmful UV rays -better skin coverage than traditional suncreams but its not clear yet whether nanoparticles can get into your body, if they do they might damage cells they might damage the environment