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3. Elements and Compounds
Elements are materials made up of one type of atom only.
Hydrogen molecule contains two hydrogen atoms bonded together, so the formula is H2.
It follows that compounds contain two or more types of atom.
The water molecule contains two hydrogen atoms bonded to one oxygen atom, so the formula is H2O.

4. Compounds: Water
Compounds are produced when elements combine. For example, water is produced in the following reaction. + 
Two water molecules react with one oxygen molecule to give water.
Word Equation
Hydrogen Oxygen  Water

5. Compounds – not mixtures
The atoms in compounds are NOT mixed together. A mixture of hydrogen and oxygen would look like:
They become bonded together during a chemical reaction. Because of this compounds have properties that are very different to the elements that they are made from.
HYDROGEN
Flammable gas.
OXYGEN
Gas in which many substances burn.
WATER
Liquid that extinguishes most fires. + 

6. Compounds – not mixtures
Black solid used as barbecue fuel
Gas in which many substances burn
Gas used in fizzy drinks and fire extinguishers
carbon oxygen  carbon dioxide

7. Naming Simple compounds.
It is easy to name simple compounds of metals and non-metals.
Write down the name of the metal
Write down the name of the non-metal but change the ending to “ide.”
1) magnesium 2) oxygen =
magnesium
oxide
1) sodium 2) chlorine =
sodium
chloride
oxygen
calcium
sulphur
silver
bromine
copper
Name of compound
Element 2
Element 1
copper bromide
silver sulphide
calcium oxide

8. Naming Simple compounds.
Name the compound formed from these elements
nitrogen
lithium
sulphur
zinc
iodine
nickel
bromine
aluminium
oxygen
tin
chlorine
sodium
magnesium
iron
Name of compound
Element 2
Element 1
iron sulphide
magnesium nitride
sodium chloride
tin oxide
aluminium bromide
nickel iodide
zinc sulphide
lithium nitride

9. Naming more complicated Compounds
Many compounds contain more than two elements. Naming them can get complicated but for those containing two elements plus oxygen the name ending usually changes to –ate.
oxygen
bromine
aluminium
sulphur
copper
Element 3
nitrogen
sodium
magnesium nitrate
magnesium
nickel sulphate
nickel
Name of compound
Element 2
Element 1
sodium nitrate
copper sulphate
aluminium bromate

10. The composition of compounds.
Compounds are very different to the elements from which they are made but there is another way in which compounds are different to mixtures.
In a mixture you can add any amount of the ingredients.
Compounds always contain a definite amount of each element. They have a fixed composition.
This is not really surprising as looking at the word equations you will have seen they always have a definite number of element atoms joined together. Na Cl O H O C Mg O

11. The formula of compounds
This means that every compound can have a formula that tells us how many of each type of atom are present. We include small slightly dropped numbers if there are more of one atom than the other.
Carbon dioxide
One carbon atom
Two oxygen atoms
Formula CO2 O C
Water
One oxygen atom
Two hydrogen atoms
Formula H2O O H

12. The formula of compounds
Activity
The formula of compounds
What is the formulae of each of the compounds shown?
(As with names, put the metal first.)
1. Titanium oxide
? titanium atom
? oxygen atoms
Formula Ti O
1 titanium atom
Formula
TiO2
2 oxygen atoms
2. Lithium Oxide Li O
? oxygen atom
? lithium atoms
Formula ?
3. Aluminium chloride
? aluminium atom
? chlorine atoms
Formula Al Cl
2 lithium atoms
1 aluminium atom
Formula
Li2O
1 oxygen atom
Formula AlCl3
3 chlorine atoms

13. The formula of compounds
Activity
The formula of compounds
Silicon chloride
? silicon atom
? chlorine atoms
Formula Cl
What is the formulae
of each of the compounds
shown? Cl Si Cl
1 silicon atom Cl
4 chlorine atoms
Formula SiCl4
Aluminium oxide
Manganese oxide O O O O Mn O Al Al
1 manganese atom
? manganese atom
2 aluminium atom
? aluminium atom
Formula Al2O3
Formula
Formula MnO2
Formula
? oxygen atoms
2 oxygen atoms
3 oxygen atoms
? oxygen atoms

14. Word Equations
Word equations can be used to describe any chemical change. (i.e. any process where the atoms become joined (bonded) in different ways).
The steps are:
Write down the name of the reactant(s) linking them with a + sign if there is more than one.
Write down an arrow
Write down the names of the products linking them with a + sign if there is more than one

15. Word Equations Write out word equations for this reaction
Activity
Word Equations
Write out word equations for this reaction
Lead reacts with oxygen to form lead oxide
Lead oxygen  lead oxide
Lead
Lead oxide
It hasn’t just mixed.
It has reacted and atoms are joined differently.
Why is lead oxide so different to both lead and oxygen?

16. Word Equations Write out word equations for the following reactions.
Activity
Word Equations
Write out word equations for the following reactions.
Limestone (calcium carbonate) is heated to make calcium oxide and carbon dioxide.
Magnesium reacts with hydrochloric acid to make magnesium chloride and hydrogen.
Methane is burnt to make carbon dioxide and water.
calcium carbonate  calcium oxide +carbon dioxide
magnesium + hydrochloric acid  magnesium chloride + hydrogen
methane + oxygen  carbon dioxide + water

17. sea water: a mixture of salts and water
Mixtures
Mixtures are, as the name indicates, mixed rather than reacted together.
This means that, unlike compounds:
1 They do not have to have any particular proportions of the various ingredients.
2 Their properties are often “an average” of the properties of their ingredients. (eg. a mixture of a black and white powder is grey!)
sea water: a mixture of salts and water
3 They are mixed, not bonded, and so are usually not too hard to separate back into their ingredients. (For example, it is easy to get salt from sea water.)

19. Separating Mixtures  Immiscible liquids
Immiscible means “doesn’t mix” and so we are talking about “mixtures” like water with cooking oil or water with petrol.
On a small scale you can simply remove the top layer using a pipette.
oil 
water
oil
water

20. Separating Mixtures Miscible liquids
Miscible means “does mix” and so we are talking about mixtures like water and alcohol or petrol with kerosine.
These are separated by boiling them as it is unlikely that they will boil at exactly the same temperature.
In order to “get back” the liquids we use a condenser. This is a tube that has cold water circulating through the outside. It cools down vapours and condenses them back to a liquid. Substances with low boiling points collect first, while those with higher boiling points collect later.

21. Distillation Equipment
Miscible liquids
Distillation Equipment
thermometer
condenser
water in
water out
electric
heater
collection
beaker

22. Separations Mixture Wanted Method Glass and water glass Sea water salt
How would you get this?
Mixture
Wanted
Method
Glass and water
glass
Sea water
salt
water
Cooking oil & water
cooking oil
Alcohol and water
alcohol
filter
evaporate
distil
pipette
distil

23. Separation Experiment
John has been given a mixture of salt, sand and water. He needs to separate them but cannot remember how.
Can you help him?
Write an experimental plan for John to follow so that he can have the sand, salt and water in separate containers.
Make sure you start off by telling him what equipment he will need.
Then he will need a step by step plan that is easy to follow.

24. Summary activities
A drag and drop activity

25. 1. Which of these is a compound?
bromine
copper
carbon dioxide
uranium

26. Which of these best describes a compound?
Two or more atoms bonded together.
Two or more elements mixed together.
Two or elements bonded together.
Two or more types of molecule mixed together.

27. Which of these could best describe compounds? Substances that:
are similar to the elements that they are made from.
can be formed when elements react together.
can be formed when elements decompose into two or more new substances.
substances with symbols in the Periodic Table.

28. What would be the name of a compound formed from sulphur, oxygen and zinc?
sulphur zincide
sulphur zincate
zinc sulphide
zinc sulphate

29. What would be the formula of a compound containing two aluminium atoms for every three sulphur atoms?
A. Al2S3 B. Al3S2
C. Al2S3 D. Al3S2

30. How would you separate a mixture of water and alcohol
How would you separate a mixture of water and alcohol. (Two miscible liquids)
filtering
chromatography
evaporation
distillation

31. What is the main technique you would use when separating a mixture of salt and sand?
filtering
chromatography
evaporation
distillation

32. Use the chromatogram to decide which dyes are in the ink.
A B C D Ink