H3 Chemistry 9813 · Study focus: H3 Chemistry: Relate electromagnetic radiation, photons and E = hf
H3 Chemistry: Relate electromagnetic radiation, photons and E = hf
Start from the governing chemical model, test it against evidence, then transfer the reasoning to an unfamiliar case.
Your success criteria
- Relate electromagnetic radiation, photons and E = hf
- Use named chemical evidence.
- Transfer the governing reason to an unfamiliar case.
Orientation and prerequisite retrieval
Photon energy is calculated from E=hf.
Frequency and wavelength are related by c=λf in vacuum.
Definitions and exact language
Substitution into c=λf requires wavelength in metres.
A 500 nm wavelength is 5.00×10⁻7 m.
Shorter wavelength corresponds to higher frequency.
Higher frequency corresponds to greater photon energy.
- Energy per mole of photons is obtained by multiplying one-photon energy by Avogadro's constant.
- A complete calculation states conversion, equation, substitution, unit and sensible significant figures.
Text alternative: Text alternative: Energy per mole of photons is obtained by multiplying one-photon energy by Avogadro's constant. A complete calculation states conversion, equation, substitution, unit and sensible significant figures.
Detailed molecular explanation
Shorter wavelength corresponds to higher frequency.
Higher frequency corresponds to greater photon energy.
Worked leaf-specific case
Energy per mole of photons is obtained by multiplying one-photon energy by Avogadro's constant.
Planck's constant carries units J s when energy is required in joules.
- A candidate writes, “Photon energy is E=h/f.” Which correction should replace it?
Open the feedback checkpoint after attempting
- Photon energy is calculated from E=hf.
Guided evidence check
Frequency has unit s⁻1 or Hz.
Wavenumber is inversely proportional to wavelength when consistent units are used.
- Which labelled diagram, spectrum or calculation would most directly disprove “500 nm equals 5.00×10⁻9 m.”?
Open the feedback checkpoint after attempting
- A 500 nm wavelength is 5.00×10⁻7 m.
Independent transfer
Intensity changes photon number flux, not the energy of each photon at fixed frequency.
A complete calculation states conversion, equation, substitution, unit and sensible significant figures.
- Design a specific chemical check that would expose the error in “One-photon energy already has units J mol⁻1.”
Open the feedback checkpoint after attempting
- Energy per mole of photons is obtained by multiplying one-photon energy by Avogadro's constant.
Misconception repair
Misconception: Brighter light gives each photon more energy at the same frequency.
Repair: Intensity changes photon number flux, not the energy of each photon at fixed frequency.
- Write leaf-specific feedback for the misconception “Brighter light gives each photon more energy at the same frequency.”
Open the feedback checkpoint after attempting
- Intensity changes photon number flux, not the energy of each photon at fixed frequency.
Practice, unseen assessment, re-test and next step
Complete the diagnostic questions, review the feedback, then attempt the final check.
After delayed re-test, continue to Compare electronic, vibrational, rotational and nuclear energy quantisation at /learning/h3-spectroscopy-quantised-molecular-energy-lesson.html.
- Review the feedback for each diagnostic question, then attempt the final check.
Open the feedback checkpoint after attempting
- Before moving on, state this boundary: A complete calculation states conversion, equation, substitution, unit and sensible significant figures.