Polymers, Giant Covalent Structures and Metallic Bonding Flashcards
What is a Polymer?
Lots of small units linked together to form a long molecule that has repeating sections, all atoms are linked by strong covalent bonds.
Why do Polymers take more energy to melt or boil?
They have larger intermolecular forces than simple covalent molecules, therefore require more energy to break them. (Solids at room temp)
How are Polymers intermolecular forces compare to Ionic or giant molecular compounds?
The intermolecular forces are still weaker than ionic or covalent, so they generally have lower boiling points than ionic or giant molecular compounds.
What is the difference between giant covalent structures and simple molecular substances?
All the atoms are bonded to each other by strong covalent bonds in Giant Covalent Bonds.
What are some properties of Giant Covalent Structures?
1) They have very high melting and boiling points, as lots of energy is needed to break bonds.
2) They don’t conduct electricity as they don’t have charged particles, not even Molton (except for some exceptions)
What are some example of Giant Covalent Structures?
Diamond and Graphite
What are Allotropes?
Different structural forms of the same element.
What are the properties of Diamond?
1) Diamond is made up of carbon atoms that each form 4 covalent bonds, makes diamond hard
2) Very high melting point, due to the covalent bonds.
3) Does not conduct electricity because of no free electrons
What are the properties of Graphite?
1) Each carbon atom forms 3 covalent bonds, creating sheets arranged in hexagons
2) No covalent bonds between layers, held together weakly, so free to move over each other.
3) High melting point, due to covalent bonds needing lots of energy to break.
4) One electron is delocalised, therefore it can conduct electricity.
What are the properties of Graphene?
1) A sheet of carbon atoms joined together in hexagons
2) The sheet is one atom thick, making it two-dimensional compound.
3) Very strong covalent bonds and incredibly light so can be added as a composite material to strengthen without adding too much weight.
4) Contains delocalised electrons and therefore can conduct electricity.
What are Fullerenes?
- Molecules of carbon, shaped like closed tubes or
hollow balls. - Made up of carbon atoms arranged in hexagons (but
can also contain pentagons or heptagons)
What can Fullerenes be used to do?
‘Cage’ other molecules as it forms around another atom or molecule,
What do Fullerenes have that allow them to be good conductors?
Large surface area, so individual catalyst molecules could be attached to fullerenes
What else can Fullerenes be used for?
Lubricants
What can Fullerenes form?
Nanotubes, tiny carbon cylinders
What are some properties of nanotubes?
1) Can conduct both electricity and thermal energy
2) High tensile strength
3) Diameter to length ratio very high
4) Can be used in electronics or to strengthen materials know as “Nanotechnology”
What do metals consist of?
Giant structure
What does metallic bonding involve?
The outer shell of the metal atoms are delocalised they are strong forces of electrostatic attraction between the positive metal ions and shared negative electrons.
What is metallic bonding?
The forces of attraction that hold the atoms together are in a regular structure are known as metallic bonding.
Metallic bonding is very strong
Name an example of a substance metallically bonded?
Alloy
What state of matter are solids at room temp?
- Most metals are solids at room temperature, due to
electrostatic forces between metals and the
delocalised sea of electrons are very strong (which
needs lots of energy to break)
What is the melting and boiling point of metals like?
Very High, due to the strong electrostatic forces
Are metals good conductors of heat or electricity?
Yes, as the delocalised electrons carry electrical current and thermal energy through the metal.
Are metals Malleable?
Yes, the layers of metals can slide over each other, making them malleable.
What is an Alloy?
A mixture of two or more metals or a metal and another element.
Why are Alloys harder than normal Metals
The different elements have different sized atoms, so when the elements are mixed with a pure metal it distorts the layers making it more difficult for them to slide over each other
