1. Elements, mixtures and compounds.
Lesson 3
Elements, mixtures and compounds.

2. What do the three diagrams below represent?

3. To be able to define, atom, element, mixture and compound
Learning objectives
To be able to define, atom, element, mixture and compound
to be able to name and give simple formula for simple elements and compounds
To be able to draw diagrams of simple elements and compounds.
To be able to write simple word and formula equations.

4. What is everything made from?
Atoms… yes everything, you, me the desk, the stars, the planets everything is made from atoms!
They are so small we can’t see them with our eyes but we can with very powerful microscopes
They are the smallest part of at element that can exist

5. Elements are found on the periodic table
Can you find…
Carbon
Hydrogen
magnesium
Iron
Lead
Zinc
All elements have symbols the first is a capital letter
Some come from their latin names
Pb- lead plumbum
Iron- Ferrous
Potassium – K kalium
What about W?

6. Atoms in elements and compounds
Elements are materials made up of one type of atom only.
Each hydrogen molecule is made up of two hydrogen atoms joined together.
Compounds contain two or more different types of atom.
The compound, water, exists as molecules.
Each water molecule consists of two hydrogen atoms joined to one oxygen atom.

7. Mixtures
A mixture is when particles are not chemically combined
It could be a mixture of elements
A mixture of compounds
Or a mixture of both elements and compounds.

8. Element, compound or mixture?

9. Element or compound?

10. A compound is not a mixture
The molecules in a mixture of hydrogen gas and oxygen gas, which have not reacted with each other, look like this…
The molecules in water, the compound made when hydrogen and oxygen react and their atoms become chemically joined to each other,

11. Making a compound – water
A compound is made when atoms of different elements react and join together.
For example, water is produced from the chemical reaction between hydrogen and oxygen.
hydrogen +
oxygen 
water
Two hydrogen molecules react with one oxygen molecule to produce two molecules of water.
Why does water have different properties to its elements?

12. Properties of a compound
A compound has very different properties to the elements from which it is made because the atoms are joined differently.
carbon
(element)
oxygen
(element)
carbon dioxide
(compound) + 

13. We can split up water by applying electricity. A chemical change.
Making compounds
You can not split up a compound by simple processes such as filtration as these do not break the chemical bonds
We can split up water by applying electricity. A chemical change.

14. Elements compounds and mixtures blob diagrams:
time to practice what we have learnt.

15. Compounds and names
By the end of GCSE this will be really easy but it may be challenging today.
Don’t worry!

16. Naming simple compounds
To name simple compounds of metals and non-metals:
1. Write down the name of the metal.
2. Write down the name of the non-metal, changing the ending of the word to “-ide”.
What is the name of the compound made when the following elements combine?
magnesium and oxygen
sodium and chlorine
oxygen and iron
magnesium oxide
sodium chloride
iron oxide

17. Naming compounds
What is the name of each compound formed by these metal and non-metal elements?
sulfur
nitrogen
chlorine
oxygen
bromine
iron
magnesium
sodium
tin
Element 1
Element 2
Compound
aluminium
nickel
zinc
lithium
iodine
iron sulfide
magnesium nitride
sodium chloride
tin oxide
aluminium bromide
nickel iodide
zinc sulfide
lithium nitride

18. Naming compounds containing oxygen
Many compounds contain more than two elements.
For compounds containing two elements plus oxygen, the ending of the other non-metal usually changes to “-ate”.
sulfur
nitrogen
bromine
nickel
magnesium
sodium
copper
aluminium
Element 1
Element 2
oxygen
Element 3
Compound
nickel sulfate
magnesium nitrate
sodium nitrate
copper sulfate
aluminium bromate

19. Practice naming compounds.

20. Composition of compounds
A compound contains atoms from different elements that are chemically joined together.
A compound always contains a particular amount of each element. It has a fixed composition.
Compound names can get quite long and complicated, so the symbols of the elements are used as a shorthand.
The symbols of the elements in a compound are combined to give the formula of the compound.
What is the formula of carbon dioxide?

21. Writing a formula A formula uses the symbols of the elements
When there is more than one atom of each element, the number is always written after the symbol.
carbon dioxide
carbon atoms = 1
oxygen atoms = 2
formula = CO2
water
hydrogen atoms = 2
oxygen atoms = 1
formula = H2O
The formula shows the ratio of atoms in a compound.

22. Questions on elements and compounds: Answer on the sheet.
homework
Questions on elements and compounds: Answer on the sheet.

24. Writing a word equation
A word equation can be used to describe any chemical reaction, i.e. any process in which atoms become joined
in different ways.
The steps for writing a word equation are:
1. On the right-hand side, put the name(s) of the reactant(s). If there are two or more reactants, link them with a + sign.
2. In the middle, draw an arrow ().
3. On the right-hand side, put the name(s) of the product(s). If there are two or more products, link them with a + sign.
reactant 1
product 1 
reactant 2
product 2 +

25. What is the word equation?
Lead reacts with oxygen to form lead oxide.
What is the word equation for this reaction?
lead
oxygen
lead oxide  +
Why is lead oxide so different to both lead and oxygen?
The lead and oxygen don’t mix; they react to form lead oxide. This means that the lead and oxygen atoms in the product are joined differently to the atoms in the reactants.
Photo credit: Irum Shahid