1. STARTER:
MATCH UP THE PROPERTY WITH A DESCRIPTION.

3. Ionic Bonding This is the transfer of electrons between atoms.
The atoms become ions because they have lost or gained electrons.

4. Covalent Bonding This is the sharing of electrons between atoms.
There are three ways of representing these bonds.

5. 2.1 – 2.4 Properties   Ionic Simple (covalent) Giant (covalent)
Metallic
Melting point  
Boiling point
Electrical/ heat conductor
Yes, when molten or in solution (aq) as allows ions to move
No, due to no overall charge
No – diamond Yes – graphite due to delocalised electrons
Yes, due to delocalised electrons
Strong covalent bonds, weak intermolecular forces
Strong electrostatic forces
Strong covalent bonds

6. Covalent Bonding Hydrogen = H2 H H H H This is a covalent bond.X H H X
This is a covalent bond.
It is strong bond formed by the pair of shared electrons in the outer shell and electrostatic attraction of the nuclei.

7. Hydrochloric acid = HCl
Covalent Bonding
Small covalent molecules you need to know about are…
Hydrogen = H2
Chlorine = Cl2
Oxygen = O2
Hydrochloric acid = HCl
Water = H2O
Ammonia = NH3
Methane = CH4

8. Covalent Bonding H O H O
melting
Forces within the molecules (covalent bonds) are very strong.
Forces between the molecules (intermolecular forces) are weak.
It is these intermolecular forces which break when a substance melts or boils.

9. Covalent Bonding
Simple covalent molecules such as H2, Cl2, O2, HCl, H2O, NH3 and CH4 all have low melting and low boiling points because the intermolecular forces are weak, so they are relatively easy to break by heating.
These structures do not conduct electricity because molecules do not have overall charges.

10. Covalent Bonding Giant Covalent structures (or macromolecules)
Silicon dioxide (silica)
Diamond
Graphite

11. Covalent Bonding Silicon dioxide (SO2)
Oxygen
Silicon
Oxygen
A silicon atom makes covalent bonds with two oxygen atoms. This means it has a full outer shell. The oxygen atoms can make a further covalent bond with other silicon atoms, hence the formation of a giant covalent structure.

12. Covalent Bonding Diamond (C)X O X O O X
A carbon atom makes covalent bonds with four other carbon atoms. This means that all carbon atoms have formed covalent bonds so that they have a full outer shells of electrons.

13. Covalent Bonding Graphite (C)X
I’m off O
A carbon atom makes covalent bonds with three other carbon atoms. One of the electrons in carbon does not form a covalent bond with another carbon atom. This means carbon forms layers which can slide over each other due to the free electrons and weak intermolecular forces between the layers.

14. 2.3 Graphite Layers of graphite slip off and leave a mark on paper.
The free e- from each C atom can

15. 2.3 Graphite Layers of graphite slip off and leave a mark on paper.
The (Delocalised)free e- from each C atom can move in between the layers, making graphite a good conductor of electricity

16. Silicon dioxide (silica)
Covalent Bonding
Silicon dioxide (silica)
Diamond
Graphite
Giant covalent structures all have high melting and boiling points (due to the strong covalent forces between all atoms).
Diamond is very hard, graphite is soft and slippery (due to the weak forces between layers).
The delocalised electrons of graphite are able to conduct heat and electricity.

17. Metallic structures
Metals are giant structures of atoms arranged in a regular pattern.
The electrons in the highest occupied energy levels (outer shell) of metal atoms are delocalised and so free to move through the whole structure. + -
So really, metals are giant structures of positive ions with electrons between the ions holding them together by strong electrostatic attractions.

18. Metallic structures
Delocalised electrons allow metals to conduct heat and electricity.
Layers of atoms mean that metal ions can slide over each other so metals can be bent and shaped. + -

19. Metallic structures
Metal alloys consist of more than one type of metal atom.
The atoms distort the layers so they cannot slide over each other. This means alloys are harder than pure metals.
Shape memory alloys return to their original shape after being deformed, e.g. in braces + -

20. 2.4 Metal Pure metals are made up of layers of one type of atoms
These slide easily over one another and therefore ………………… ……………………………………… ……………………………………… ………………………………………

21. 2.4 Metal Pure metals are made up of layers of one type of atoms
These slide easily over one another and therefore metals can be bent and shaped

22. polymers Polymers are repeating chains of covalently bonded monomers.
The properties of polymers depend on the conditions they were made under.

23. polymers Low density (LD) and high density (HD) poly(ethene)
Small number of particles per volume
High number of particles per volume
Ethene molecules joined in a polymer
These are made of the same monomers but the conditions they are made are different so they have different properties.

24. polymers Low density (LD) poly(ethene)
Made using high pressure and with a trace of oxygen.
Chains are branched and can’t pack together (hence the low density)

25. polymers High density (HD) poly(ethene)
Made using a catalyst at 50oC and slightly raised pressure. They can pack closely (hence the high density).
It is stronger than low density poly(ethene)

26. polymers Intermolecular forces (forces between chains) Weak
Strong cross links
Softens and resets
Does not melt
Thermosoftening polymer
Thermosetting polymer

27. Nanoscience
Very, very small structures; nanometers (nm) in size
Only contain a few hundred atoms
Have different properties to the same materials in bulk.
Have a high surface area to volume ratio

28. Nanoscience
Fullerene is an example of a nanoparticle made of hexagonal arrangements of carbon
Possible uses of fullerenes;
Catalysts
Drug delivery
Lubricants
Reinforcing
Possible uses of other nanoparticles;
New computers
New catalysts
New coatings
Sensors
Stronger and lighter construction materials
New cosmetics

29. 2.5 Nanoscience Structures are: ……………………………………… or a few hundred atoms
Show different properties to same materials in bulk
Have high surface area to volume ratio

30. 2.5 Nanoscience Structures are: 1-100 nm in size or
a few hundred atoms
Show different properties to same materials in bulk
Have high surface area to volume ratio

31. 2.5 Nanoscience Titanium oxide on windows
Titanium oxide reacts with sunshine, which breaks down dirt
Silver and socks
Silver nanoparticles in socks can prevent the fabric from smelling