Topic 2 -Bonding, structure, and the properties of matter Flashcards
Describe the structure of an ionic compound.
- They are structured in a giant ionic lattice
- There are very strong electrostatic forces of attraction between oppositely charged ions, in all directions.
Why do ionic compounds have high melting/boiling points?
Due to the strong bonds between ions, which require a lot of energy to overcome.
Why can’t molecular compounds conduct electricity?
They aren’t charged, so there ar no delocalised electrons or ions to carry charge through the substance.
What is a polymer?
A polymer is a substance made up of many smaller monomers linked to form a long molecule with repeating sections.
Why do simple molecular structures have low melting/boiling points?
- The covalent bonds are very strong, but the intermolecular forces are very weak, so they require very little energy to overcome.
Why do giant covalent structures have high melting/boiling points?
- Lots of energy is needed to overcome the very strong covalent bonds.
What are examples of giant covalent structures?
1.diamond
2.graphite
3.silicon dioxide
What is the structure of a diamond?
Each carbon atom forms 4 covalent bonds in a rigid giant covalent structure
What is the structure of Graphite?
Each carbon atom forms 3 covalent bonds to create layers of hexagons. Each carbon atom also has one delocalised electron.
What is silicon dioxide?
Sand
What are the allotropes of Carbon?
- Diamond
- Graphite
- Graphene
- Fullerenes
Why is graphite a good lubricant?
- No covalent bond between layers
- So they’re only held together weakly
- So they can move over each other freely which makes it slippery.
What is graphene?
1 layer of graphite
Why is graphene useful to improve strength, and be used in electronics?
- Network of covalent bonds makes it very strong and it is light
- Because it has delocalised electrons it can conduct electricity.
What are fullerenes?
Molecules of carbon shaped like closed tubes or hollow balls.
What are the properties of nanotubes?
1.ratio between length and diameter is high
2.good conductor
3.high tensile strength
Explain the structure of metallic bonding?
- Electrons in outer shell are delocalised
- There is a strong force of electrostatic attraction between the positive metal ions, and the sea of electrons
- This holds the metal together in a strong, regular structure
Why are metals solids at room temp?
1.The electrostatic forces of attraction between the metal ions and the sea of delocalised electrons are strong, and require lots of energy to overcome.
Why are alloys harder?
- When another element is mixed with a pure metal, the new different sized atoms distort the regular layers
- This makes it harder to slide across eachother.
How large are coarse particles, fine particles and nano particles?
Diameter of:
1.2500nm-10000nm
2. 100nm-2500nm
3. 1nm-100nm
What are the uses of nanoparticles?
1.Catalysts
2.Nanomedicine
3.electric circuits
4.Anti-bacterials
5.Cosmetics
What shape is a buckminster fullerene?
A Hollow sphere
What can fullerenes be used for?
Transport medicine around the body.
