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Doc Brown's Chemistry
KS3
SCIENCE-Chemistry QCA Unit 7G Particle model of solids, liquids and
gases
More advanced GCSE work based on 7G:
GCSE m/c tests
* States of Matter (g l s)
KS3 Biology Quizzes *
KS3 Chemistry Quizzes
*
KS3 Physics Quizzes
*
 mixed Science Quizzes
7G
Particle model of solids, liquids and
gases
 QCA 7G
"Particle model of solids, liquids and
gases" Multiple
Choice Questions for Science SATs revision on gases, liquids and solids
- particle models, properties, explaining the differences between them.
 7Gwf1-4
four
handy linked word-fill
worksheets * 7Gwf2 * 7Gwf3 *
7Gwf4 *
The BIG hard on-line
crossword
puzzle 
(with letter hints), printout of the BIG version
OR the
smaller EASIER
(with letter hints),
printout
of the smaller EASIER version
3 linked
States1mp -matching pair
exercises on the states of matter
or States2mpDD - drag & drop version or printout
* States2mp *
States2mpDD * States3mp *
States3mpDD *
The
7G crossword and word-fill
* KS3 Science multiple Choice Quizzes for
chemistry, worksheets and practice chemistry questions for pupils revising Key
Stage 3 science SATs tests revision help for secondary students *
In the unit - you should learn how
- the particle model can be used to explain
differences between solids, liquids and gases.
- experimental evidence relates to theories and
models to explain things.
- to use the particle model to relate scientific theories and evidence.
- to evaluate whether evidence does or does not
support explanations of observations
- to describe and explain observations using the
particle model.
- to classify materials as solid, liquid
or gas and explain that some materials are 'difficult' to classify.
- to describe materials as being made of particles and describe the movement and
arrangement of them,
- to use the particle model to explain
phenomena, eg the mixing of liquids,
the expansion of a metal bar, 'dancing' dust particles etc.
- to do labelled drawings to describe the
arrangement and movement of particles in solids, liquids and gases.
Its handy if you
- have experience of identifying (classifying) solids,
liquids and gases and describing the properties of each.
- know that the same material can exist as a
solid, liquid and gas.
- have seen that melting solids and
freezing liquids are the opposite of each other.
- have seen and understand what we mean by
dissolving, evaporation
and condensation take place.
- have some ideas how to separate gases,
liquids and solids
Some important words for you to understand, use and spell correctly:
- words with a precise meaning in scientific
contexts, eg evidence, theory, model, ?
- words and phrases relating to the particle
model, eg particle, diffusion, gas pressure, vibration, ?
- words relating to scientific enquiry, eg
evidence, data, ?
How can we explain evidence from typical experiments?
- comparing the masses of identically-sized blocks of two or
three different materials such as wood, glass and metal - this tells us
eg how dense things are, particles have different mass, closer together, ..?
- putting one small coloured crystal into a beaker of cold water
and one into a beaker of hot water - how fast do the particles spread
and why?
- trying to fit a metal bar into a gauge before and after strong
heating - shows expansion - the hotter particles vibrate more and spread
out.
- opening a perfume bottle at arm’s length -
particles move to our nose!
- heating one end of a metal rod that has paperclips attached by
petroleum jelly - heat moves as vibration from higher to lower
temperatures
- trying to depress the plungers of three sealed syringes, one
containing a solid, one a liquid and one a gas - which is the most
easily compressed? - the gas - has the most space between particles.
- putting weights on the end of a thin wire -
stretches and then snaps
How are theories created?
- you share and discuss ideas and suggest theories
based on experimental data (evidence).
- sometimes new evidence results that doesn't
fit in and shows the theory needs to be changed and improved.
What are the differences between solids, liquids and gases?
- classify materials and justify your choice in terms of
the properties of solids, liquids and gases,
- but
that some materials are difficult to classify and can you explain why?
- imagine what you might see if the materials
could be seen using an immensely powerful microscope.
- describe solids, liquids and gases in a
way that fits the evidence and your scientific knowledge, eg a solid is made
of tiny grains all glued together
- do a summary table to classify materials as solid, liquid or gas
and show their similarities and differences.
- take care if you use, or come across, other
'particle' terms eg atom, molecule.
- don't confuse microbes, cells and particles and the
differences will need to be made explicit.
How can the particle model explain the differences between solids,
liquids and gases?
- models can be used to explain things which cannot be
observed in a direct way.
- solids, liquids and gases are made up of tiny
particle and the differences can be
explained in by the distance between, and the motion of their particles.
- particle theory can explain some phenomena,
eg
diffusion of a gas, mixing of liquids, expansion of a metal bar.
How can the particle model explain other phenomena?
-
apply a model to new observations to explain behaviour
eg
-
placing coloured crystals on agar gel and observing the diffusion
of colour
-
placing distinct layers of water and ink in plastic syringes
and observing the mixing of colour over a short period of time
-
observing dust particles in a beam of light
-
explain your observations in terms of particles
- gas particles are moving around all the time
so ...
- gas pressure is caused by particles hitting the walls of the
container
- gases mix by diffusion, eg by mixing bromine
and air, or nitrogen dioxide and air (both visible in gas jars)
-
having seen the collapsing can experiment
...
-
explain their observations using the particle theory
-
identify where there are contradictions in ideas to explain the
collapsing
-
describe gas particles as moving all the time and pushing against
surfaces
-
explain that the can collapses because there are fewer air
particles on the inside hitting 'out' than on the outside hitting 'in'.
Copyright
© Dr W P Brown 2000-2010 All rights reserved for revision notes, quizzes,
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