Q23 (b)

Criteria	Marks
Explains how the de Broglie hypothesis addressed limitations in the Bohr–Rutherford atomic model	4
Describes how the de Broglie hypothesis addressed limitations in the Bohr–Rutherford atomic model OR explains how the de Broglie hypothesis addressed a limitation in the Bohr–Rutherford atomic model	3
Demonstrates some understanding of the de Broglie hypothesis and/or a limitation in the Bohr–Rutherford atomic model	2
Provides some relevant information	1

Sample answer: De Broglie’s hypothesis suggested that electrons in the hydrogen atom are in a stable state when they formed standing waves. As the electron was no longer considered an accelerating charge, the problem of accelerating charges producing electromagnetic radiation was resolved. Additionally, the problem of why electrons had only certain allowed orbits was resolved by the criteria of an electron orbit only being allowed when it consisted of a whole number of electron wavelengths.