C2.2.1-3 How structure influences the properties and uses of substances Flashcards
Are the intermolecular forces of a substance that consists of simple molecules weak or strong?
What makes these types of substance melt or boil?
- There are weak forces between the molecules
- When the intermolecular forces are overcome, not the covalent bonds
Why do substances that consist of simple molecules not conduct electricity?
Because the molecules do not have an overall electric charge
Why do ionic compounds have high melting and boiling points?
Because of the large amounts of energy needed to break the many strong bonds
Why do ionic compounds conduct electricity when melted or dissolved in water?
Because the ions are free to move and carry the current
What structure do diamond, graphite and silicon dioxide have?
Giant covalent structures/lattices
How many bonds does carbon have in graphite, what kind of bonds, and what does this form?
Each C to 3 others
COVALENT
Slidey layers
Graphite has layers that are free to slide over each other. Why? What effect does this have on the physical features of graphite?
- There are NO COV. BONDS between layers
- Graphite is SOFT AND SLIPPERY
Why can graphite conduct electricity and heat?
One electron from each carbon atom is delocalised (similar to metals which also have delocalised electrons)
Carbon can form fullerenes with…
…different numbers of carbon atoms
What are fullerenes used for? (4 points)
- Used for drug delivery into the body
- LUBRICANTS
- CATALYSTS
- In nanotubes for reinforcing materials (e.g. tennis rackets)
What shape is the structure of fullerenes?
Hexagonal rings of carbon atoms`
Give two examples of a simple molecules and one example of a macromolecule
- Simple= wax, methane
- Macromolecule= SiO2= sand
