Chemistry
Topic 2 Atoms and elements
Unpicking misconceptions
1 Identifying misconceptions
Encourage students to share their ideas about atoms and elements by providing stimulus for free
flowing discussion. This will give you the opportunity to identify and correct any misconceptions.
Some ways to engage students in dialogue is to offer visual representations and opportunities for
three-dimensional modelling, especially for diatomic molecules. Direct observation and experience
of chemical and physical changes and active investigation of the physical properties of the
elements will stimulate students to share explanations and allow you to assess the accuracy of
their understanding.
 Key questions and strategies
All the resources mentioned may be found in Topic 2 Unpicking Misconceptions.

Multiple choice hinge questions are provided in the presentation  Activity 1: Hinge
questions. These questions give students the opportunity to instantly review and correct their
misunderstandings.
Follow-up activities for each question are presented in the Word document
Activity 1: Hinge questions worksheet. Each slide, with accompanying questions,
represents one activity. These are intended to be used according to the lesson objectives.
Possible uses are either as a mini plenary, midway through the lesson, in which case the
questions could be the next activity in the lesson, or as a final plenary with the questions being
set as homework .

The voting quiz ( Activity 2: Atom, element or molecule?) and accompanying voting cards
(Voting cards and follow-up questions) can be used as a starter or plenary. This quiz
and accompanying voting cards provide an opportunity for instant feedback. Students will
mostly choose the correct answer, which will help to build their confidence. Follow-up
questions and subsequent dialogue can be used to deepen learning beyond the initial
responses.
Some suggested follow-up questions are given with the voting cards. To support with the
demand of this exercise students could write a definition and some examples on the back of
the voting card in order to remind them of the distinguishing features of atoms, elements and
molecules. They could then keep these in an envelope stuck into their books.

Written formative feedback should be part of your assessment for learning (AFL) practice,
along with verbal reminders, sharing of progress markers and praise for the completion of
short-term targets. Comments should focus on developing explaining skills.
This topic demands that students use their understanding of the particle model to explain the
make-up of substances, in particular atoms and elements, and begin to understand chemical
change in terms of particles. Useful comments, such as ‘ensure you include the word because
in your answer’, ‘include a particle diagram in your explanation’ and ‘you have shown clearly
how particles explain this observation – to extend include word or symbol equations in your
work’ will focus on this skill.
(These and other AFL strategies are described fully in P. Black, C. Harrison, B. Marshall, D.
Wiliam and C. Lee (2003) Assessment for Learning: Putting it into Practice Buckingham: Open
University Press.)
Teach Better KS3 Chemistry Dynamic Learning © Hodder and Stoughton 2013
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Chemistry • Topic 2 • Atoms and elements

A thorough mastery of key vocabulary is central to avoiding misconceptions. Students can
often understand the concepts but get confused with the labelling. To avoid this ensure all
subject specific vocabulary is spoken and written frequently and referred to throughout the
topic. Expect students to use the correct scientific language in any class discussion and clarify
any misuse by a passive repeat of the correct word.
Some method of recording key vocabulary for constant reference throughout a topic is
essential. Possible methods include a key word bookmark, flashcards with key words or a
display of key words for the topic on the wall. More essential, however, is constant modelling
of the language by the teacher; once a word has been introduced, use it whenever possible.
(For a more detailed perspective on building language skill in secondary learners, see H.
McLachlan and L. Elks (2008) Secondary Language Builders. St Mabyn, Cornwall: Elklan.)
2 Common misconceptions

Particles being misrepresented in diagrams.
To overcome this encourage the use of a key as this will remind students that different
substances need to be represented as different sizes or colours in order to distinguish them.
This becomes more important when the concepts of atoms, elements and molecules are
introduced.

The presence of elements in our bodies.
Students will be aware that we contain certain substances – iron in our blood and calcium in
teeth and bones. However, these exist in our bodies as ions (a concept they will not meet
until late KS3/KS4) and there may be confusion when they are reacting calcium metal with
acid for example, or looking at the physical properties of iron as a hard, dense metal.
To tackle these queries explain that these substances are in our bodies but in a different
form which is physically and chemically different from the pure elements we are studying.

The invention (rather than discovery) of elements.
Students often quote who by and when elements were invented. It is important here to focus
on the discovery of elements; all naturally occurring elements were present when the Earth
formed – an important idea for the concept of conservation of mass. Scientists discovered
them at different points and this is closely related to their reactivity.

Expansion of matter is due to increase in particle size rather than in particle
spacing.
Students should appreciate the fixed nature of particle size. When drawing changes of state
it is important to ensure the particles individually remain unchanged; it is the arrangement
which alters. By drawing attention to this fact students should become accustomed to the
idea that when a solid expands it is the arrangement of the particles, i.e. the spaces
between them, which alters.

‘Water exists in all three states but other substances do not.’
Changes of state are often only understood in terms of water because this is the most
familiar example and all three states can be investigated in the laboratory. Students can
therefore develop the idea that water exists in all three states but other substances do not.
Students will often say oxygen is a gas or copper is a solid without qualifying this with the
temperature. To overcome this make sure you use several substances in your examples
and make a habit of drawing particle diagrams at different temperatures.
Teach Better KS3 Chemistry Dynamic Learning © Hodder and Stoughton 2013
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Chemistry • Topic 2 • Atoms and elements

‘Mass, volume and density are all the same thing.’
Each quantity has its own unit and specific meaning, for example density is a measure of
how much substance is in a fixed volume. Its unit is kg/m 3, i.e. mass divided by volume.
A good way to explore this concept is using blocks of different materials with uniform volume
– students will be able to see they are the same size and shape and therefore volume.
By feel they could then predict and measure the mass. Since only the substance is
changing, you can present density as a property of the substance. Follow-up discussions
could include question such as ‘what will happen to the mass if I have twice the volume?’
and similar questions to reveal the mathematical relationships.
3 Overcoming the big misconceptions
In Topic 2 Unpicking Misconceptions you will find presentations on overcoming two major
misconceptions. Once you have watched the presentations, you can use the content of the slides
to work through the misconceptions with your students.
Misconception 1: Mass, volume and density
Misconception 2: Elements in our bodies
Teach Better KS3 Chemistry Dynamic Learning © Hodder and Stoughton 2013
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