AQA · GCSE · Combined Science

    Course version: 8464 · Version from Sept 2018

    The electrons are arranged at different distances from the nucleus…

    Full specification wording

    The structure of an atom: The electrons are arranged at different distances from the nucleus (different energy levels). The electron arrangements may change with the absorption of electromagnetic radiation (move further from the nucleus; a higher energy level) or by the emission of electromagnetic radiation (move closer to the nucleus; a lower energy level).

    Electrons occupy energy levels at set distances from the nucleus, not a continuous spread.

    Checked against the AQA 8464 specification (opens in a new tab) on .

    • Point 4 of 4
    • 4 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    Electrons occupy energy levels at set distances from the nucleus, not a continuous spread. The lowest available level is filled first, and each level holds a limited number of electrons. An electron can move to a higher level by absorbing electromagnetic radiation of the right energy; it then falls back to a lower level by emitting electromagnetic radiation. For example, atoms can also be excited by heating in a flame; as the electrons drop back to lower levels, they emit visible light of characteristic colours, which is why flame tests work. The energy gap between levels fixes the frequency of radiation absorbed or emitted, linking electron arrangement to spectra.

    What earns the marks

    • Describe electrons as arranged in energy levels at different distances from the nucleus, with lower levels closer to the nucleus.
    • Explain that absorption of electromagnetic radiation moves an electron further from the nucleus to a higher energy level.
    • Explain that emission of electromagnetic radiation occurs when an electron moves closer to the nucleus to a lower energy level.
    • Relate the size of the energy gap to the energy of the radiation absorbed or emitted.
    • Apply the model to a context such as flame colours or line spectra produced by excited atoms.

    Common mistakes and how to put them right

    • Saying electrons can sit at any distance from the nucleus.

      Put it right by stating they occupy fixed energy levels at set distances.

    • Reversing absorption and emission.

      Put it right by linking absorption to moving further out and a higher level, and emission to moving closer in and a lower level.

    • Treating energy levels as evenly spaced or unlimited.

      Put it right by noting each level has a limited capacity and gaps between levels differ.

    Exam tips

    • Use the phrases 'higher energy level' and 'further from the nucleus' together when describing absorption.
    • Use the phrases 'lower energy level' and 'closer to the nucleus' together when describing emission.
    • If a question gives a spectrum or flame colour, link the observed radiation to an electron dropping between named levels.

    Try the lesson

    The start of the The structure of an atom: The electrons are arranged at different distances from the nucleus (different energy levels). The electron arrangements may change with the absorption of electromagnetic radiation (move further from the nucleus; a higher energy level) or by the emission of electromagnetic radiation (move closer to the nucleus; a lower energy level). lesson, made from checked teaching notes for this specification point.

    Have a go first

    In an atom, the electrons are arranged in energy levels. Which statement describes the arrangement of these electrons?

    Listen

    Electrons occupy energy levels at set distances from the nucleus, not a continuous spread. The lowest available level is filled first, and each level holds a limited number of electrons. An electron can move to a higher level by absorbing electromagnetic radiation of the right energy; it then falls back to a lower level by emitting electromagnetic radiation. For example, atoms can also be excited by heating in a flame; as the electrons drop back to lower levels, they emit visible light of characteristic colours, which is why flame tests work. The energy gap between levels fixes the frequency of radiation absorbed or emitted, linking electron arrangement to spectra. A strong answer earns marks for these points. Describe electrons as arranged in energy levels at different distances from the nucleus, with lower levels closer to the nucleus. Explain that absorption of electromagnetic radiation moves an electron further from the nucleus to a higher energy level. Explain that emission of electromagnetic radiation occurs when an electron moves closer to the nucleus to a lower energy level. Relate the size of the energy gap to the energy of the radiation absorbed or emitted. A common slip: Saying electrons can sit at any distance from the nucleus. Instead, stating they occupy fixed energy levels at set distances. Exam tip: Use the phrases 'higher energy level' and 'further from the nucleus' together when describing absorption.

    See it

    A top-down flowchart. The first box says electrons are arranged in energy levels at different distances from the nucleus. An arrow leads to a box for absorption of electromagnetic radiation, then to a box saying the electron moves further from the nucleus, then to a box for a higher energy level. From there an arrow leads to a box for emission of electromagnetic radiation, then to a box saying the electron moves closer to the nucleus, and finally to a box for a lower energy level.
    It shows that absorbing electromagnetic radiation moves an electron to a higher energy level further from the nucleus, and emitting electromagnetic radiation moves it to a lower energy level closer to the nucleus.

    Put it in order

    Put these steps in the order they happen.

    1. 1. Lower energy level
    2. 2. Electron moves closer to the nucleus
    3. 3. Electron moves further from the nucleus
    4. 4. Emission of electromagnetic radiation
    5. 5. Electrons arranged in energy levels at different distances from the nucleus
    6. 6. Absorption of electromagnetic radiation
    7. 7. Higher energy level

    Key words

    Say what each word means before you turn the card.

    Energy levels

    Try answering aloud or in your head before turning the card.

    Absorption of electromagnetic radiation

    Try answering aloud or in your head before turning the card.

    Emission of electromagnetic radiation

    Try answering aloud or in your head before turning the card.

    Flame colours

    Try answering aloud or in your head before turning the card.

    See every definition
    Energy levels
    Electrons are arranged at different distances from the nucleus, and these different distances are called energy levels.
    Absorption of electromagnetic radiation
    The electron arrangements may change by taking in electromagnetic radiation, which moves an electron further from the nucleus to a higher energy level.
    Emission of electromagnetic radiation
    The electron arrangements may change by giving out electromagnetic radiation, which moves an electron closer to the nucleus to a lower energy level.
    Flame colours
    Atoms can be excited by heating in a flame, and as the electrons drop back to lower levels they emit visible light of characteristic colours.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A top-down flowchart. The first box says electrons are arranged in energy levels at different distances from the nucleus. An arrow leads to a box for absorption of electromagnetic radiation, then to a box saying the electron moves further from the nucleus, then to a box for a higher energy level. From there an arrow leads to a box for emission of electromagnetic radiation, then to a box saying the electron moves closer to the nucleus, and finally to a box for a lower energy level.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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    Test your understanding of The structure of an atom: The electrons are arranged at different distances from the nucleus (different energy levels). The electron arrangements may change with the absorption of electromagnetic radiation (move further from the nucleus; a higher energy level) or by the emission of electromagnetic radiation (move closer to the nucleus; a lower energy level).

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