Chapter 2 - Strucute And Properties Flashcards
Why do ionic compounds conduct electricity when melted into liquid or when dissolved in water
Because the ions are free to move. This allows them to carry electrical charge
Why do some ionic solids dissolve in water
Because the water molecules can split up the lattice.
Why do simple molecules have little attraction for each other
These bonds act only between the atoms within the molecule
Do substances made of simple molecules have low or high melting and boiling points
Low
Why do simple molecules not conduct electricity
Molecules have no overall charge and so cannot carry electrical charge
What does intermolecular forces mean
The forces of attraction between molecules
Why do substances made of simple molecules have low melting points and boiling points
There are weak intermolecular forces between simple molecules
Why do giant covalent structures have very high melting points
Every atom in the structure is joined to several other atoms by strong covalent bonds. It takes an enormous amount of energy to break down the lattice and so substances have very high melting points
What are two similarities between diamond and graphite
They are both a form of carbon.
The atoms are covalently bonded.
What are two differences between diamond and graphite
Diamond has a regular three dimensional giant structure.
Graphite has the carbon atoms in giant flat two dimensional layers
There are no covalent bonds between the layers so they slide over each other
Why does graphite conduct heat and electricity
One electron from each carbon atom is delocalised, delocalised electrons allow graphite to conduct heat and electricity
What are some of the applications for fullerenes
- Drug delivery into the body
- Lubricants
- Catalysts
- Reinforcing materials
Why do ionic compounds have high melting points and high boiling points
Ionic compounds are solids at room temperature so a lot of energy is needed to overcome the ionic bonds to melt the solids
Why can the layers of graphite slide over each other quite easily
There are only weak intermolecular forces between the layers
Why are metals useful for making wires, rods and sheet materials
Metal atoms are arranged in layers. When a force is applied the layers of atoms can slide over each other. They can move into a new position without breaking apart, so the metal bends or stretches into a new shape.
What is an alloy
A mixture of metals or metals mixed with other elements
Why are alloys harder than pure metals
The different sized atoms in the mixture distort the layers in the metal structure and make it more difficult for them to slide over each other.
What happens when you hear a shape memory alloy
It returns to its original shape
Why are shape memory alloys useful
They can be bent or deformed into a different shape
Give an example of where shape memory alloys can be used
Dental braces
Why are metals good conductors of heat and electricity
Metal structures have delocalised electrons. The delocalised electrons move throughout the giant metallic lattice and can transfer energy quickly
What does Must Every Pupil Be Perfect stand for
Methane Ethane Propane Butane Pentane
What happens when changing the reaction conditions of a polymer
The properties of the polymer that is produced changes
Give an example of a thermosoftening polymer
Poly(ethene)
