topic 2 - bonding, structure, properties of matter

Question 1

structure of an ionic compound

Answer 1

• giant ionic lattice
• ions closely packed
• very strong electrostatic forces between opposite charges
• very very strong

Question 2

properties of ionic compounds

Answer 2

• high melting and boiling points
• takes lots of energy to overcome strong attractions
• solid - ions tightly packed so don’t conduct electricty
• liquid - ions free to move and conduct electricity and flow

Question 3

what is covalent bonding

Answer 3

• non metals and non metals share electrons in their outer shells to make covalent bonds
• electrostatic forces make it very strong
• having a full outer shell gives them the structure of a noble gas - very stable
  dot and cross diagram

Question 4

properties of simple molecular substances

Answer 4

• very low melting and boiling points
• the forces of attraction between molecules is very weak
• don’t conduct electricity bc no ions
• liquid and gas at room temp

Question 5

what are simple molecular substances and examples

Answer 5

• made up of molecules containing few atoms joined by covalent bonds
• oxygen/hyrdogen/chlorine - O2/ H2/ Cl2

Question 6

polymers

Answer 6

• all of its atoms linked with covalent bonds
• larger intermolecular forces between molecules than simple molecular substances therefore more energy needed to break
• solid at room temp

Question 7

diamond

Answer 7

• very high melt and boil point
• don’t have charged particles so don’t conduct electricity
• each carbon atom forms 4 covalent bonds
• very rigid

Question 8

graphite

Answer 8

• very high melt and boil point
• each atom forms 3 covalent bonds creating layers of hexagons with a delocalised electron to carry electrical charge therefore conducting electricity and thermal energy

Question 9

graphene

Answer 9

• sheet of carbon atoms joined in hexagons
• sheet is one atom thick
• very stong but very light
• contains delocalised electrons so can conduct electricity

Question 10

fullerenes

Answer 10

• carbon shaped like hollow balls
• hexagons
• used to deliver drugs around body
• huge surface area - good catalysts

Question 11

nanotubes

Answer 11

fullerenes can form nanotubes
- tiny carbon cylinders
- length : diameter ratio very high
- conduct electricity and thermal energy
- used in nonotechnology and to strengthen materials bc very light

Question 12

properties of metals - metallic bonding

Answer 12

• electrostatic forces and sea of delocalised electrons - very strong and loads of energy to break
• high melt and boil point
• good conducts of heat and electricity bc of delocalised electrons
• malleable - layers can slide - bent/hammered/rolled

Question 13

what is metallic bonding

Answer 13

electrostatic attraction between positive metal ions and delocalised electrons

Question 14

what are alloys

Answer 14

• 2 or more metals /// a metal and another element
• HARDER - different sized atoms distorts the layers so they cant slide over each other

Question 15

what are the 3 things that the force of attraction of states of matter depends upon

Answer 15

1. the material
2. temp
3. pressure

Question 16

solids

Answer 16

• strong forces hold particles in a fixed regular lattice arrangement
• defined shape and volume bc the particles don’t move
• particles dont move they - vibrate - hotter the more vibrations

Question 17

liquid

Answer 17

• weak forces randomly arranged particles free to move past but stay close together
• definite volume but random shape
• particles constantly moving in random directions
• expand when heated

Question 18

gases

Answer 18

• very weak forces of attraction and can move far apart
• dont keep definite shape or volume
• will always fill a container
• constantly moving in random directions
• expand when heated so pressure increases

Question 19

process of solid to gas - melting and boiling

Answer 19

1. solid heated particles more energy and weakens the forces of solid
2. at certain temp MELTING POINT particles have enough energy and are free from positions MELTING
3. liquid heated and particles more energy and break bonds
4. at certain temp BOILING POINT they have enough energy to break their bonds BOILING/EVAPORATING - gas

Question 20

process of gas to solid - condensing and freezing

Answer 20

1. gas cools and particles don’t have enough energy therefore bond together
2. at BOILING POINT so many bonds have formed between the gas particles to become a liquid -CONDENSING
3. liquid cools particles have less energy to move and bond start to form - FREEZING
4. liquid is now a solid and at the melting point so many bonds have formed

Question 21

whats the diameter of a nanotube

Answer 21

1nm and 100nm

Question 22

how do you work out the SA : V ratio

Answer 22

SA / V (surface area divided by volume)

Question 23

whats the SA : V ratio of a nanoparticle and uses

Answer 23

• very high SA : V ratio - the surface area is much bigger than the volume

Question 24

uses of nanoparticles

Answer 24

• catalysts - high SA : V ratio
• nano medicine - deliver drugs
• electric circuits - conductors of electricity
• cosmetics - moisturisers bc oily

Question 25

nano particles in suncreams - risks

Answer 25

• not fully understanding the risks
• better than normal suncream to protect skin from UV rays and have better skin coverage
• but we don’t know if they can get into your body and damage our cells
• and when they are washed away we don’t know if they might damage the environment