8E Atoms and Elements
Lesson 2 (or most appropriate for your scheme of work): How do
we get other materials?
Learning objectives
 That compounds contain elements that are chemically combined.
 To represent and explain chemical reactions by word equations, models or
diagrams.
Learning outcomes
 To have increased the sophistication of their particle model to include the
“chemical joining” of different types of atom in a compound.
 To explain compound formation in terms of atoms joining using equations,
diagrams & models.
Resources
For demonstration: a liquid filled syringe, particle block/Lego models, iron filings,
sulphur and a magnet.
For activity 2. – bags of mints, toffees, and minty toffees.
Context
Pupils are expected to think back to the particle model taught in Year 7.
Lesson Outline
Activity 1 – identifying misconceptions
 Pupils complete sentences presented on board or OHT. Aim is to identify
misconceptions, test model by applying it and to challenge it by spotting its
current limitations (in describing difference between compounds and
mixtures).
1. Liquids can be compressed because….
2. We cannot see grains of salt once they have dissolved in water
because…………..
3. A balloon gets bigger when the heating is turned up because………..
4. We can separate a mixture of sulphur and iron using a magnet
because…………
5. Salt dissolves in water but sand does not because………….
6. Iron reacts with oxygen to make iron oxide when it rusts
because…………
7. We cannot get iron back from rust (iron oxide) because………

Go through pupils’ responses with class. This provides an opportunity to deal
with misconceptions in their explanations (have a liquid filled cylinder on hand
to confirm it cannot be compressed; have block models handy to show how a


grain of salt breaks down into individual particles; demonstrate the separation
of iron and sulphur using a magnet).
Identify problem: our current understanding of the particle model allows us to
explain all statements except 4 and 7. Pose the question “how do we explain
why an iron and sulphur mixture can be separated but iron cannot be obtained
from iron oxide (rust)?”
On poster paper pupils make their own suggestions using pictures of particles
Iron and sulphur

Iron oxide
Go through suggestions with class – conclude that in compounds atoms are
chemically joined to each other, perhaps representing that with bonds drawn
between atoms.
Activity 2 – tasty modelling!

1.
2.
3.
4.
5.
6.
7.
Issue bags of sweets to groups and ask pupils to use them to model
a solid element
a mixture of two elements
a solid compound
a liquid compound
a gaseous element
a mixture of an element dissolved in a compound
use a piece of sugar paper and a pen to draw ‘+’ and ‘’ . Use the sweets
to represent a reaction where two elements react to form a compound (iron +
oxygen  iron oxide) . This links back really well to statement 7 in the
previous activity and sets the scene for understanding work equations. Follow
this on by writing the word equation of the board, sticking the sweets to the
board and finally adding particle drawings with bonds evident on the drawing
of iron oxide.