topic 2 - bonding, structure, properties of matter Flashcards
structure of an ionic compound
- giant ionic lattice
- ions closely packed
- very strong electrostatic forces between opposite charges
- very very strong
properties of ionic compounds
- 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
what is covalent bonding
- 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
properties of simple molecular substances
- 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
what are simple molecular substances and examples
- made up of molecules containing few atoms joined by covalent bonds
- oxygen/hyrdogen/chlorine - O2/ H2/ Cl2
polymers
- 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
diamond
- 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
graphite
- 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
graphene
- sheet of carbon atoms joined in hexagons
- sheet is one atom thick
- very stong but very light
- contains delocalised electrons so can conduct electricity
fullerenes
- carbon shaped like hollow balls
- hexagons
- used to deliver drugs around body
- huge surface area - good catalysts
nanotubes
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
properties of metals - metallic bonding
- 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
what is metallic bonding
electrostatic attraction between positive metal ions and delocalised electrons
what are alloys
- 2 or more metals /// a metal and another element
- HARDER - different sized atoms distorts the layers so they cant slide over each other
what are the 3 things that the force of attraction of states of matter depends upon
- the material
- temp
- pressure
solids
- 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
liquid
- 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
gases
- 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
process of solid to gas - melting and boiling
- solid heated particles more energy and weakens the forces of solid
- at certain temp MELTING POINT particles have enough energy and are free from positions MELTING
- liquid heated and particles more energy and break bonds
- at certain temp BOILING POINT they have enough energy to break their bonds BOILING/EVAPORATING - gas
process of gas to solid - condensing and freezing
- gas cools and particles don’t have enough energy therefore bond together
- at BOILING POINT so many bonds have formed between the gas particles to become a liquid -CONDENSING
- liquid cools particles have less energy to move and bond start to form - FREEZING
- liquid is now a solid and at the melting point so many bonds have formed
whats the diameter of a nanotube
1nm and 100nm
how do you work out the SA : V ratio
SA / V (surface area divided by volume)
whats the SA : V ratio of a nanoparticle and uses
- very high SA : V ratio - the surface area is much bigger than the volume
uses of nanoparticles
- catalysts - high SA : V ratio
- nano medicine - deliver drugs
- electric circuits - conductors of electricity
- cosmetics - moisturisers bc oily
nano particles in suncreams - risks
- 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
