C2.2 Structure and Properties Flashcards
Explain why NaCl is a solid at room temperature
It has a giant ionic lattice
It is held together by ionic bonds which are very strong
Therefore it has a high melting point
Explain why oxygen is a gas at room temperature
It has a simple molecular structure
It is held together by weak intermolecular forces
Therefore it has a low melting point
Explain why iron is a solid at room temperature
It has a giant metallic structure
It is held together by strong metallic bonds
Therefore it has a high melting point
Explain why iron conducts electricity as a solid and liquid
It has delocalised electrons which are free to move throughout the metal structure
Explain why graphite conducts electricity
Each carbon has only 3 bonds.
This leaves one delocalised electron
Which is free to move
Explain why diamond doesn’t conduct electricity
Each carbon has 4 bonds.
It has no free electrons
Explain why sodium chloride doesn’t conduct electricity as a solid
The ions can’t move
Explain why sodium chloride conducts electricity when dissolved
The ions are free to move
Explain why carbon dioxide doesn’t conduct electricity
Its electrons aren’t free to move
Explain why molten magnesium chloride can conduct electricity
The ions are free to move
Explain why ammonia is a gas at room temperature
It is a simple molecular substance
Its held together by weak intermolecular forces
Therefore it has a low melting point
Explain why methane is a gas at room temperature
It is a simple molecular substance
It is held together by weak intermolecular forces
Therefore it has a low melting point
Explain why silicon dioxide has an unusually high melting point
It has a giant covalent structure
It has strong covalent bonds
Which require a lot of energy to break
Explain why graphite has a very high melting point
It has a giant covalent structure
which is held together by strong covalent bonds
which require a lot of energy to break
What property makes diamond useful for sharpening knives
It is very hard
Explain why diamond is so hard
It is arranged in a giant lattice
Each carbon has 4 bonds
The lattice is rigid
Explain why thermosetting polymers have high melting points
They have crosslinks between the chains
made with covalent bonds
which are strong
Explain why high density polyethene has a higher melting point than low density polyethene
High density polyethene has a crystalline structure and strong forces between the polymer chains
What is a nanoparticle
a particle between 1nm and 100nm in size
Why do nanoparticles have different properties?
Because they have a much bigger surface area
What are the risks of nanoparticles?
Their large surface area makes them very reactive/explosive (nano aluminium)
Nanoparticles are easily absorbed by the lungs and there is little research into the long term health risks.
What conditions can be changed to make High Density Polyethene rather than Low Density Poly Ethene?
Pressure
Temperature
