Unit 2: Chapter 2 - Structure and Properties Flashcards
Giant ionic Structures
Boiling Point?
Solubility?
Conduction of Electricity?
These lattice structures have high boiling and melting points.
Most ionic compounds are soluble in water.
When in liquid state, ions are free to move around. As the ions carry an overall charge, it can conduct electricity.
Simple Molecules
Boiling Point?
Solubility?
Conduction of Electricity?
Intermolecular forces?
Low boiling and melting points.
Most simple molecules are at liquid and gas state at room temp, however there are some solids at room temp but low melting points.
Simple molecules do not conduct electricity as there is no overall charge.
INTERMOLECULAR FORCES
Intermolecular forces are strong between atoms within molecules.
However intermolecular forces are weak between molecules.
Giant Covalent Structures
Melting and Boiling point?
Strength? Why?
Soluble?
Explain why graphite is different
What are fullerenes?
High melting and boiling points.
Insoluble
Very strong as they have covalent bonds.
GRAPHITE
Although graphite has covalent bonds it is only bonded to three other carbon atoms. They form hexagon shapes. In this way, the carbon atoms slide off when they is force against something.
Bonding in Graphite
With carbon atoms in graphite, there is 1 delocalise electron on the outer shell of the atom, similar to the electrons in a metallic structure.
These free electrons allow graphite to conduct electricity unlike diamond.
FULLERENES
Fullerenes consist of hexagonal rings of carbon. These objects look like cages and produces many exciting possibilities. For example, it could potentially deliver drugs to specific parts of bodies, as well as catalysts and lubricants.
Giant Metallic Structures
Why can pure metals slide over each other easily?
What properties does this give?
Compare alloys and pure metals.
What are shape-memory alloys?
Pure metal is arranged closely-packed, regular rows. Because of the regular arrangement, these atoms are able to slide over each other, which is why pure is soft and bendy.
Alloys are a mixture of elements and are more brittle than pure metal. This is because the regulars rows are disrupted by different sized elements and so it makes it hard for atoms to slide over each other. This makes alloys hard to bend.
SHAPE-MEMORY ALLOYS
Some alloys are able to return to their original shape after being deformed when heated.
For example, the heat of the body pulls the metal attached to the broken bone to be pulled together.
This is also useful for dentists when using braces.
The Properties of Polymers
Which two factors affect the properties of polymers?
How do we make LDPE and HDPE
What are thermosoftening and thermosetting polymers?
How do they differentiate?
Polymers are made from crude oil.
The properties of polymers depends on two factors:
- The monomers used to make it
- The condition we choose to carry out the reaction.
DIFFERENT MONOMERS
- Some polymers, such as nylon contain more than two different monomers which can make nylon withstand very large forces without snapping.
DIFFERENT REACTION CONDITIONS
- There are two different types of poly(ethene). These are LOW-density poly(ethene) and High-density poly(ethene). These are formed under different conditions.
- High pressure + O2 -> LDPE
- Catalyst + 50C + pressure -> HDPE
HDPE has a higher softening temp and is stronger than LDPE.
THERMOSOFTENING AND THERMOSETTING POLYMERS
- Thermosoftening polymers are made up on individual polymer strands than are tangled together. There are no covalent bonds connected to these individual strands. Each monomer is covalently bonded to form these strands. The intermolecular forces between these plastic strands are weak and when we heat these polymers, the intermolecular forces are broken. When the polymer cools down, the intermolecular forces bring the polymer back together.
- Thermohardening polymers have monomers that covalently bonded with each other and are CROSS-LINKED. Even at very high temps, the polymer won’t soften but begin to char.
Nanoscience
Current uses?
Future Developments?
Possible Risks?
Nanometre = 1x10 (-9) metres
- Titanium Oxides is used on the glass of windows to break down dust particles when sunshine triggers a chemical reaction.
- Titanium Oxide and Zinc Oxides are used in modern sun-creams which act as physical barriers to block the sunlight. These are more effective than conventional UV blocker suncreams.
- The cosmetic industry are investing into nano science by making the nano particles go deeper into the skin and absorbed deeper into the skin.
FUTURE DEVELOPMENTS?
Nanotubes could be potentially used in incredibly small electronic circuits. Nanotubes can be used to treat people with asthma and can detect traces of gas present in the breath of asthmatics before an attack.
Nano wires would help computers speed up and increase memory capacities.
Nano suits are also being developed as bulletproof vests that can also be sprayed on. There would also be biosensors that could be able to send medical data back to medical teams.
POSSIBLE RISKS
- Large surface area make them very dangerous and could cause a violent explosion if a spark is triggered.
- Breathing nanoparticles in would damage the lungs significantly and could enter bloodstream.
