C2 Flashcards
How can you work out the percentage yield?
Actual mass of product obtained/maximum theoretical mass of product x 100
What is an Endothermic reaction?
A reaction which takes in energy from its surroundings.
E.g Electrolysis
What is an exothermic reaction?
A reaction that transfers energy to its surroundings.
E.g Combustion
How do you find the empirical formula of a compound?
1: Find the Masses
2: Look up the Ar values
3: Masses / Ar
4. Find the ratio
What do Covalent Bonds do?
Share electrons to fill their outer shell.
What is an Isotope?
Different atomic forms of the same element,which have the same number of protons but a different number of neutrons.
What is Ionic Bonding?
When atoms lose/gain electrons to form charged particles (Ions) to get a full electron shell.
What do Ionic Compounds have?
A regular lattice structure. There are very strong electrostatic forces of attraction between oppositely charged ions,in all directions.
What properties do Ionic compounds have?
High Melting and Boiling points,due to the strong attractions between the ions.
Can conduct electricity when molten-due to free ions carrying electronic current.
Dissolve easily in water.
What are the two types of Giant Covalent substances?
Simple molecular substances,and giant covalent structures.
What are the properties of a simple molecular substance?
The forces of attraction between these molecules are weak.
Therefore they have a low boiling and melting point.
Don’t conduct electricity,as there is no ions.
How is a covalent simple molecular substance formed?
The atoms form very strong covalent bonds to form small molecules of several atoms.
What are Giant Covalent Substances?
All the atoms are bonded together by strong covalent bonds. They also have a giant lattice structure.
What are the properties of a Giant Covalent substance?
Don’t conduct electricity,even when molten-apart from Graphite.
High melting and boiling points,due to the strong covalent bonds.
What are three examples of Giant Covalent substances?
Diamond
Silica
Graphite
What are the main features of Diamond?
Forms 4 covalent bonds in a rigid giant covalent structure.
This makes diamond the hardest natural substance,so it’s used for Drill Tips.
What are the main features of Graphite?
Each Carbon atom forms 3 covalent bonds. This creates layers,which are free to slide over each other,so it’s soft and slippery.
There is a weak intermolecular force between the layers.
Good conductor of heat and electricity,due to each carbon atom having a free electron.
What are Nanoparticles?
Really tiny particles,which are about 1-100 nanometers across. They contain fullerenes,which are molecules of carbon shaped link a hollow ball or closed tubes.
How are Nanotubes made?
The fullerenes in the Nanoparticles are joined together. These covalent bonds makes the carbon nanotubes very strong.
What are some of the new uses of Nanoparticles?
Industrial Catalysts
For stronger,lighter building materials
In electric circuits for computer chips.
What are polymers?
Atoms in a long chain held together by strong covalent bonds.
What are Thermosoftening Polymers?
Individual chains of polymers,held together by weak intermolecular forces,which are free to slide over each other.
Don’t have cross linking between chains,therefore the forces are easy to overcome to melt it.
What are thermosetting polymers?
Plastics with strong intermolecular forces between the polymer chains called cross links.
Doesn’t soften when heated-they are strong,hard and rigid.
What affects a Polymer’s properties?
How it is made.
Low density polythene is made by hearing ethene to about 200 degrees Celsius,under high pressure. Used for plastic bags.
High density polythene is made at lower conditions with a catalyst,so it’s more rigid.
