Recall that changes in atoms and nuclei can a generate radiations over a…

The idea

This statement covers two directions of a single idea. Part a: changes inside atoms and nuclei generate electromagnetic radiation across a wide frequency range. An electron dropping to a lower energy level in an atom emits a photon, often visible or ultraviolet; changes within the nucleus, such as a nucleus settling into a lower energy state, emit gamma radiation at much higher frequency. Part b: the reverse also happens, because atoms and nuclei can be changed by absorbing radiation from a range of frequencies. An atom absorbs a photon of the right energy and its electron moves to a higher level; a nucleus can absorb high-frequency radiation and be left in an excited state. A useful method is to pair each emission with its matching absorption and to note that the frequency range is wide, from low to very high.

What earns the marks

• States that changes in atoms and nuclei generate radiation over a wide frequency range.
• States that changes in atoms and nuclei can be caused by absorption of a range of radiations.
• Gives an example of an atomic change emitting or absorbing radiation, such as an electron moving between energy levels.
• Gives an example of a nuclear change emitting or absorbing radiation, such as gamma emission from an excited nucleus.

Common mistakes and how to put them right

• Describes only emission and ignores absorption.

  Put it right by stating that absorption of radiation can also change atoms and nuclei.

• Claims that atoms and nuclei emit radiation at only one frequency.

  Put it right by stating that the range of frequencies is wide.

• Confuses atomic and nuclear changes.

  Put it right by keeping electron energy-level changes with atoms and gamma emission with nuclei.

• Says absorption leaves an atom or nucleus unchanged.

  Put it right by stating that absorption causes a change, such as excitation.

Exam tips

• Check whether the question asks about generating radiation or about being changed by absorption, because the statement covers both.
• Use the phrase wide frequency range to signal that you know more than one type of radiation is involved.
• Give a named example, such as an electron changing energy level or a nucleus emitting gamma radiation, to make your answer precise.