What do atoms look like? | 16-18 years

In this session, students explore how the scanning tunnelling microscope (STM) can be used as a tool for investigating atoms. Students encounter an excerpt from Richard Feynman’s lecture ’There’s plenty of room at the bottom’, stimulating thinking about nanochemistry.

This activity fits within or towards the end of a series on atoms and atomic structure.

Learning objectives

Students will understand that:

• The STM is used to photograph and move atoms.
• Atoms are nanometre-sized particles.
• A vision for science in the future can be realised.

Sequence of activities

Introduction

Introduce the learning activities by asking students what they think atoms look like, for a list of items too small to see and for their ideas about the kinds of properties atoms have.

Activity: Seeing atoms

1. Give students the worksheet ’Seeing atoms’ and the briefing sheet ‘The scanning tunnelling microscope’.
2. Organise the students into groups and give support as they:
   • Respond to the questions.
   • Prepare to feedback to the class with each group taking responsibility for one picture on the worksheet.

Plenary 1

In a plenary, draw out ideas from the responses with further questions:

• Why can’t we see atoms?
• In what ways do the pictures differ from their ideas about what atoms look like?
• How has the STM contributed to our understanding of atoms?
• Why is it useful to be able to move atoms around as we wish?
• What might sub-atomic particles look like?

Activity: There’s plenty of room at the bottom

Distribute the worksheet ‘There’s plenty of room at the bottom’ and ask students to return to their groups. Again, circulate and offer support as they:

1. Respond to the comprehension activity.
2. Prepare responses to feedback.
3. Select a spokesperson to give the feedback.

Plenary 2

In a plenary:

1. Invite spokespersons to give responses.
2. Pose questions to widen the perspectives of the students:
   • Should our society be afraid of these developments?
   • How might nanotechnology develop in the future?
   • How should we respond when scientists make bold statements?
   • Use responses as a basis for stimulating reflection on the development of our understanding of atomic structure.

Feedback

Give written feedback indicating the extent to which students have understood key ideas, including the latest developments about nanotechnology.

Commentary

Through discussion and through feedback from other groups, students develop coherent thinking and reflect on their own ideas about the latest developments in our understanding of atoms and atomic structure. These ideas can be fed into a summary piece of writing that draws on all aspects of work on atomic structure. In addition, teacher questions probe thinking, pushing to extend ideas beyond the normal boundaries.

Written feedback will confirm where thinking has developed, highlight weaknesses in understanding and points to work on.

Answers

Picture 1

1. Nickel: Ni, atomic number 28, mass number 59; Xenon: Xe, atomic number 54, mass number 131.
2. Nickel is on top (red), xenon is underneath as the body of the zit (blue).
3. Purely speculative examples: copper (top) and krypton (body); carbon (top) and argon (body).
4. The atoms would not have colours. These have been added by the computer.

Picture 2

1. 1s²2s²2p⁶3s²3p⁶3d⁹4s².
2. They probably have fewer electrons, creating the dents in the wave pattern.
3. and 4. Electrons – they can behave like waves and particles.

Picture 3

1. 100
2. By moving each individual iron atom.
3. 248 x 11 x 10-3 = 2.728 nm.
4. It reflects the sense of atoms as the basic, original building blocks for all substances.

Picture 4

1. A spike.
2. The outermost electrons are shared across the structure of the metal surface. If copper atoms were placed individually on the surface of a different metal, they would also probably appear as spikes.
3. Electrons.
4. Scientists can make the molecules they really want without having to mix chemicals.

There’s plenty of room at the bottom

1. Atoms and sub‑atomic particles.
2. The talk was given over 40 years ago and so presented a vision for the future. No one else was talking in this way and much of what Feynman was talking about has happened.
3. Mixing chemicals, shaking and fiddling around.
4. Being able to pick up atoms and put them wherever they are needed.
5. Yes, at least to some extent.
6. Probably with amazement.
7. Resolve by discussion.