c2 bonding structure and the properties of matter

Question 1

How can a particle change state?

Answer 1

• putting in or taking out energy:
  putting in - heating. eg melting and boiling requires energy to break forces of attraction in solid
  taking out - cooling. eg freezing and condensing reforms forces of attraction
• stronger forces of attraction = more energy to break forces, higher MP

Question 2

particle arrangement in solids

Answer 2

• particles close together with little space between, in regular pattern
• fixed shape, particles vibrate
• fixed volume, hard to compress

Question 3

particle arrangement in liquids

Answer 3

• close together with little space between, free to move/flow over each other
• no fixed shape, fits container
• fixed volume, hard to compress

Question 4

particle arrangement for gases

Answer 4

• widely spaced and free to move
• no fixed shape, fill container
• no fixed volume, easy to compress

Question 5

limitations of the particle model of states of matter

Answer 5

• presents all particles as solid spheres. particles are different shapes and not solid
• assumed that there are no forces between particles. forces have major impact on MP and BP

Question 6

match the different types of bonding to the reacting elements involved

Answer 6

ionic - metal and non metal
covalent - non metal and non metal
metallic - metal and metal

Question 7

what should you get after drawing diagram for ionic bonding

Answer 7

atoms with mismatch dots/crosses in brackets with charge and number of the ion

Question 8

what should you get after drawing diagram for covalent bonding

Answer 8

overlapping circles with mismatch dots/crosses in intersection (energy level diagram)
- OR no circles (dot and cross diagram)
- OR lines (stick diagram)

Question 9

structure of ionic compounds

Answer 9

• form giant 3D structures: giant ionic lattice
• strong electrostatic forces of attraction (ionic bonds) in all directions, sometimes no shown in diagram
• each ion is surrounded by oppositely charged ions

Question 10

properties of ionic compounds

Answer 10

• high MP and BP as lots of heat energy needed to break electrostatic forces of attraction
• cannot conduct electricity when solid as ions are held in place by electrostatic forces of attraction. when melted of dissolved in water, ions are free to move and carry charge

Question 11

pros and cons of dot and cross diagram

Answer 11

• dots and crosses: clear where electrons are coming from
• dont tell us shape of molecule

Question 12

pros and cons of two-dimensional stick diagram

Answer 12

• covalent bond is stick: cannot tell which electron came from which atom
• dont tell us about the outer electrons that are not in bonds
• dont tell us shape of molecule

Question 13

pros and cons of three dimensional stick diagram

Answer 13

• tells us shape of molecule

Question 14

pros and cons of ball and stick model for lattices

Answer 14

• shows ions in 3d
• shown as spaced apart when ions are actually close together
• only show tiny part of giant lattice, impression that they are much smaller than they actually are

Question 15

pros and cons of space filling diagram for lattices

Answer 15

• shows how closely packed they are
• may be difficult to see 3d layers
• only show tiny part of giant lattice, impression that they are much smaller than they actually are

Question 16

what is a double/triple covalent bond and give examples

Answer 16

when atoms require 2/3 more electrons, so share 2/3 pairs of electrons
double eg oxygen, co2
triple eg nitrogen

Question 17

examples (on spec) and properties of small covalent molecules

Answer 17

• low MP and BP, gas or liquid at room temp, as little energy needed to overcome weak intermolecular forces
• as size increases, intermolecular forces increase
• do not conduct electricity, as they have no overall charge

Question 18

properties and examples of giant covalent molecules

Answer 18

• millions of covalent bonds
• solid at room temp, high MP and BP
  diamond, silicon dioxide, graphite

Question 19

properties of diamonds and link to structure

Answer 19

• hundreds of carbon atoms each bonded to four other carbon atoms
• very hard due to lots of strong covalent bonds
• high MP and BP as lots of energy needed to overcome strong covalent bonds
• cannot conduct electricity as there are no free electrons

Question 20

properties of silicon dioxide and link to structure

Answer 20

• silicon and oxygen covalently bonded
• high MP and BP as lots of energy needed to break strong covalent bonds

Question 21

properties graphite

Answer 21

• soft and slippery
• high MP and BP
• good conductor of electricity and heat

Question 22

properties of graphite and link to structure

Answer 22

• carbon atoms each bonded to three other carbon atoms in hexagonal rings
• soft and slippery as hexagons form layers with no covalent bonds between, used as lubricants
• high MP and BP as lots of energy needed to overcome strong covalent bonds
• good conductor of electricity and heat as delocalised electrons carry charge/heat

Question 23

allotropes of carbon

Answer 23

diamond
graphite
graphene
fullerenes

Question 24

properties of graphene and link to structure

Answer 24

• single layer of graphite, one atom thick
• good conductor of electricity as delocalised electrons carry charge
• very strong due to lots of strong covalent bonds
• high MP and BP as lots of energy needed to overcome strong covalent bonds

Question 25

what are fullerenes

Answer 25

hollow balls or closed tubes, ususally hexagonal, can also be 5 or 7

Question 26

first fullerene discovered

Answer 26

buckminsterfullerene - 60 carbon atoms - hollow sphere - rings of 6 or 5 carbon atoms

Question 27

uses of fullerenes

Answer 27

- deliver drugs in body as they can form around molecules - lubricants in machines to reduce friction between moving parts - catalysts to speed chemical reactions

Question 28

what are carbon nanotubes and what are properties

Answer 28

fullerenes shaped into cylinders with very high length to diameter ratio - high tensile strength so can be stretched - good conductor of electricity as delocalised electrons carry charge - good conductor of heat

Question 29

uses of carbon nanotubes

Answer 29

- reinforce material eg in high end tennis rackets

Question 30

what is a polymer and what are their properties

Answer 30

- very large molecule with strong covalent bonds - double covalent bond of monomers become single to join together - solid at room temp as lots of energy needed to overcome relatively strong intermolecular forces between polymer molecules

Question 31

how to draw a polymer

Answer 31

Question 32

structure and bonding of metals

Answer 32

- metals consist of giant structures of atoms arranged in regular layers - outer electrons are delocalised, meaning metal atoms are positive ions. strong electrostatic forces between, metallic bonds - metallic bonds are very strong

Question 33

properties of metals and link to structure

Answer 33

- high MP and BP as lots of energy required to overcome strong metallic bonds - good conductors of heat and electricity delocalised electrons carry charge and thermal energy - malleable as layers of atoms can slide over each other

Question 34

problem of metals and solution

Answer 34

some pure metals eg copper, gold, iron, aluminium are not hard enough to use, need to be harder. make an alloy: mix with other metals, meaning different sizes of atoms distorts layers, making them harder to slide over each other.

Question 35

different particles and their diameters

Answer 35

coarse / dust / PM10 2.5 x 10^-6 and 1 x 10^-5 or 2 500nm and 10 000nm fine / PM2.5 1 x 10^-7 and 2.5 x 10^-6 or 100nm and 2500nm nano 1 x 10^-9 and 1 x 10^-7 or 1nm and 100nm

Question 36

describe surface area to volume ratio for particle sizes

Answer 36

as diameter decreases by 10 times, SA:Vol ratio increases by 10 times meaning nanoparticles have huge SA:Vol ratio, so much smaller quantity of material needed compared to material with normal particle size.

Question 37

uses and risks of nanoparticles

Answer 37

- useful for catalysts, medicine, electronics, deoderant, cosmetics - however nanoparticles can be absorbed into body and enter cells, however effects are unknown and must be studied