COVALENT BONDING AND CARBON Flashcards
Describe the structure of nanotubes
Hexagonal rings of carbon atoms
Arranged in a hollow cylinder
Explain why graphite can act as a lubricant
There are no covalent bonds between the layers
So there are free to slide over each other
Describe the structure of graphite
Each carbon atom forms 3 covalent bonds with 3 other carbon atoms
The atoms form layers made of hexagonal rings
Name 3 properties of diamond
High melting and boiling points
Does not conduct electricity
Very hard
Explain why Diamond is hard
It has a giant covalent structure
It has strong covalent bonds between atoms
Which are hard to break
Explain why polymers have high melting points relative to substances made of small molecules
They have much larger molecules
So stronger intermolecular forces
Which require more energy to overcome
Describe the structure of substances consisting of small molecules
Small molecules made up of atoms held together by strong covalent bonds.
Weak intermolecular forces act between the molecules.
Explain why larger molecules have higher melting and boiling points than smaller ones
They have stronger intermolecular forces
Which require more energy to overcome
Describe the structure of fullerenes
Molecules made of rings of carbon atoms will hollow shapes
Name the first fullerene that was discovered
Buckminsterfullerene
How many bonds does each carbon atom have in diamond?
4
When a substance consisting of small molecules is melted or boiled , identify the forces that are overcome
Intermolecular forces
Name 3 uses of nanotubes
Nanotechnology, electronics and materials
Describe what happens to electrons in covalent bonding
They are shared between atoms
Explain why a Buckminsterfullerene can be used as a lubricant
The molecules have a spherical shape so can roll over each other
Give 2 uses of Graphene
Electronics and composites
Describe the structure of graphene
One layer of graphite
Give two typical properties of substances made of small molecules
Low melting and boiling points
Do not conduct electricity
Name the type of structure that is made of billions of atoms covalently bonded together
Giant covalent structure
Name the three main types of substances formed from covalently bonded atoms
Small molecules, very large molecules, and giant covalent structures
Explain how graphite conducts electricity, making full reference to its structure and bonding
Each carbon atom has three bonds only
There is therefore one delocalised electron per carbon atom
The delocalised electrons are free to carry charge through graphite
Explain why simple molecular substances have low melting points
Weak intermolecular forces require little energy to overcome
Give 3 examples of substances with a giant covalent structure
Diamond
Silicon dioxide
Graphite
Define polymer
A very large molecule made of smaller molecules joined together
Name the type of substances that form covalent bonds when they react together
Non metals
