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Radioactivity

Electron orbits and energy levels

  • 2 things to know
  • Paper 1

Overview

Electrons orbiting at fixed distances called energy levels, why outer electrons are held least tightly, moving between levels by absorbing or emitting electromagnetic radiation, why only certain energies are absorbed, and how atoms give out light or ionise.

What you need to know

Answer each one before you reveal it.

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Key term

How do electron energy levels explain which energy an atom can absorb, and how the atom gives out light?

Key term

Describe the arrangement of the electrons around the nucleus of an atom.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Describe the arrangement of the electrons around the nucleus of an atom.

    Model answer

    The electrons orbit the nucleus at a number of fixed, set distances from it.

  2. 2

    Can an electron in an atom sit at any distance at all from the nucleus?

    Model answer

    No, only certain set distances from the nucleus are allowed.

  3. 3

    Which electrons in an atom are held least tightly by the nucleus?

    Model answer

    The outer electrons, because they are furthest from the positive nucleus.

  4. 4

    What name is given to the fixed distances at which electrons orbit the nucleus?

    Model answer

    They are called energy levels, or shells.

  5. 5

    How does the energy of an electron change as its orbit lies further from the nucleus?

    Model answer

    An electron in an orbit further from the nucleus has more energy.

  6. 6

    What happens to an electron in an atom when it absorbs electromagnetic radiation?

    Model answer

    It moves to a higher energy level, further from the nucleus.

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