topic 7- structures (inc ionic, giant covalent, simple covalent, polymers and metals) Flashcards
Features of giant covalent structures
- high melting point
- no specific formula
- 1 large molecule
Ball and stick diagrams
(i) this component represents bonds between atoms
(ii) this component represents atoms
(i) stick
(ii) ball
Why do giant covalent structure ps have very high melting points?
As they have very strong covalent bonds between the atoms
Why is diamond hard?
It has lots of strong covalent bonds
Why doesn’t diamond conduct electricity?
It has no delocalised electrons in its structure
Why does diamond have a high melting point?
A lot of energy is needed to break the strong covalent bonds. Therefore it has a high melting point
In diamond, each carbon atom is bonded to __ other carbon atoms by strong covalent bonds
4
What is carbon?
A giant covalent structure
What shape are the carbon atoms in graphite’s layers?
Hexagonal (6-sided)
Graphite has ____ intermolecular forces keeping layers together
Weak
Why is graphite very soft?
It’s layers can easily slide over one and another
In graphite, each carbon atom is bonded to __ other carbon atoms by strong covalent bonds
3
Why can graphite conduct electricity?
- each carbon atoms forms three bonds
- this means that there is a delocalised electron from every carbon atom
- this electron can move freely, therefore graphite is a good electrical conductor
What are fullerenes?
Molecules of carbon atoms that take up hollow structures. Their structure is usually carbon atoms arranged in hexagonal (6-sided) rings, but pentagonal (5-sided) and heptagonal (7-sided) carbon rings can also be found.
What type of molecule is buckminsterfullerene?
A simple molecule because of its fixed size
What shape is the buckminsterfullerene?
Spherical
What is the formula for buckminsterfullerene?
C60
Common uses of spherical fullerenes:
- catalysts
- lubricants
- as vehicles for transporting drugs into our bodies
Carbon nanotubes are…
Cylindrical fullerenes
Why are carbon nanotubes exceptionally strong for their size?
because of strong covalent bonds between carbon atoms
uses of cylindrical fullerenes:
- in electronics
- in nanotechnology
- for strengthening materials (e.g. tennis racket frames)
Carbon nanotubes are often called molecular wires, why?
As they have a tiny diameter but can be incredibly long