Topic 2 - Bonding, Structure and Properties of Matter Flashcards
What is Ionic bonding?
A metal and a non-metal react, the metal atom loses electrons to form a positive ion and the non-metal gains these electrons and becomes a negative ion. The two are attracted by electrostatic forces.
What is Covalent bonding?
Non-metal atoms bond together, they share electrons to fill their outer shells. They are attracted to each other by electrostatic forces.
What are simple molecular substances?
They are made up of molecules containing a few atoms which are joined together by covalent bonds.
- H2
- CL2
- H2O
- CH4
What is a polymer?
A polymer is a long molecule which is made up of repeating units.
What are Giant covalent structures? Give examples.
Large structures where all of the atoms are bonded by strong covalent bonds.
- Diamond
Each carbon forms 4 covalent bonds - Graphite
Each carbon forms 3 covalent bonds to create layers of hexagons. Each carbon has 1 delocalised electron. - Silicon Dioxide
A giant structure of silicon and oxygen (sand)
What are Allotropes?
Different structural forms of the same element in the same physical state.
Why is graphite soft and slippery?
There are no covalent bonds between the layers so they’re free to move over each other. One layer is a sheet of graphene.
What are fullerenes?
Fullerenes are molecules of carbon, shaped like closed tubes or hollow balls. They have a “cage” like structure.
What can fullerenes be used for?
- They can be used to deliver drugs into the body as they trap another atom or molecule inside.
- They can also form nanotubes which are used in nanotechnology.
- They can be used to strengthen materials without adding much weight.
What was the first fullerene to be discovered?
Buckminsterfullerene - C60 and forms a hollow sphere.
What is metallic bonding?
Electrons in the outer shell of the metal atoms are delocalised. This allows an electric / thermal current to be carried through the whole structure.
Why are alloys better for certain jobs?
Alloys are often harder than pure metals because when two elements are mixed, the different sized molecules distort the layers and makes them stronger. In pure metals, the layers are equal and slide across each other.
What is the equation for SA:V ratio?
Surface Area divided by Volume.
Give some examples of nanoparticle uses.
- deliver drugs right into the cells where they’re needed
- they can be used in tiny electric circuits because they conduct electricity
- silver nanoparticles have antibacterial properties and can be used to make surgical masks / dressings
