Structure, Properties and Uses of Substances Flashcards
What is the melting point of an ionic compound like?
High
What is the boiling point of an ionic compound like?
High
Why do ionic compounds have high melting and boiling points?
Because the ions are held together by strong electrostatic attraction which requires a lot of energy to overcome.
What is a useful property of melted ionic compounds?
They can conduct electricity.
Are ionic compounds soluble?
Yes, very.
What is a useful property of dissolved ionic compounds?
They can carry an electric current.
What are three characteristics of simple molecules?
- Low melting and boiling points.
- Mostly liquids or gases at room temperature.
- Don’t conduct electricity.
What are the intermolecular forces between simple molecules like?
Very weak.
What are two properties of most macromolecules?
- High melting and boiling point.
* Not conductive.
How many covalent bonds does each carbon atom in a diamond contain?
Four
What is the hardest natural substance?
Diamond
What is a use of diamond?
Drill tips
How many covalent bonds does each carbon atom in graphite make?
3
How is the carbon in graphite arranged?
In layers that can easily slide over each other.
What holds the layers in graphite together?
Weak intermolecular forces.
What happens to the extra electrons in the carbon in graphite that don’t form bonds?
They become delocalised which means that graphite can conduct heat and electricity.
How does a metal’s structure affect its malleability?
Because the atoms are arranged in a regular structure, they can easily slide over each other which makes them easy to bend and shape.
Why are metals conductive?
They have delocalised electrons that can move freely around the metal so can carry current and heat energy through the structure.
What is an alloy?
Two or more metals mixed together.
Why are alloys useful?
The different sized atoms disrupt the structure of the metal meaning that the layers don’t slide over each other as easily making them harder.
What is an example of a smart material?
Shape memory alloys
What are shape memory alloys?
A material that can be shaped but will return to its original shape when heated.
What are two used of shape memory alloys?
Glasses frames and dental braces.
What is a nanoparticle?
A particle between 1 and 100 manometers across.
What is a property of silver nanoparticle a that regular silver doesn’t have?
They can kill bacteria.
What are uses of nanoparticles?
- Catalysts - huge surface area to volume ratio
- Water purity tests
- Building materials
- Sun creams and deodorants
- Lubricants
- Computer chips
What are fullerenes?
A type of molecule made of carbon shaped into balls or tubes. The carbon atoms are arranged in hexagonal rings.
What are three used of fullerenes?
- Lubricants and catalysts
- Medicine
- Reinforcing materials
How are the polymer chains in thermosoftening polymers arranged?
Loose and tangled together, held together by weak intermolecular forces.
What is a thermosoftening polymer?
A polymer that can be melted and shaped into a new shape.
What is the structure of a thermosetting polymer?
The polymer chains are connected by cross links that hold the structure solidly in place. This means that they don’t melt, only burn.
What are four properties of thermosetting polymers?
- Strong
- Hard
- Rigid
- No melting/boiling point
How is LDPE made?
By heating ethene to 200 degrees under high pressure.
What are two used of LDPE?
Plastic bags and bottles.
Under what conditions is HDPE made?
At a low temperature and pressure in the presence of a catalyst.
What are two used of HDPE?
Water tanks and drainpipes.
