Flashcards in C2.2 Structure and Properties Deck (16):
Why do ionic compounds have high melting and boiling points?
There are so many strong ionic bonds to break and to separate the ions, you have to overcome the forces of attraction. It takes a lot of energy.
Why can't a solid ionic compound conduct electricity?
It's in a fixed position and the ions can't move around to conduct anything.
What forms of an ionic compund can conduct electricty?
molten and liquid because the particles can move around
Do covalent bonds have low melting and boiling points?
Why do convalently bonded substance have low boiling and melting points?
They have weak intermolecular forces.
why can't simple molecules conduct electricity?
They have no overall charge so they can't conduct electricty
Properties of diamond
hard, high melting and boiling points and are insoluble in water
What are the forms of carbon?
diamond, graphite, graphene, silicon, buckminsterfullerene
Why are alloys harder than pure metals?
they are a mixture of metals so the sixe of the particles are different so they have no layers and they can't slide over each other
Example of a shape memory alloy
How to make Low Density Poly Ethene?
High pressure and oxygen
How to make High Density Poly Ethene?
use a catalyst at 50 degrees and high pressure
What is a thermosoftening polymer?
a polymer that forms plastics which can be softened by heat, then remoulded into different shapes as they cool down and set
What are thermosetting polymers?
They are polymers that can form extensive cross-linking between chains. resulting in rigid materials which are heat-resisitant
Uses of nanoscience
sunscreen, cleaning glass, cosmetics, tumours, antibacterials