Chemistry · Chapter 6

Light, Wavelength and Photon Energy

Drag either slider. Wavelength and frequency always move opposite ways, because c = λν never changes. The photon energy follows frequency straight up.

The wave itself drawn to scale

Can this photon break a bond? energy per mole

Green light, 532 nmVisible. Your eye is most sensitive right here.
Wavelength λ
532 nm
Frequency ν
5.635 × 1014 s-1
One photon
3.734 × 10-19 J
Same photon
2.33 eV
One mole of photons
225 kJ/mol
From a 5 mW pointer
1.3 × 1016 photons/s

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What to notice
Short waves hit harder
Halve the wavelength and you double both the frequency and the photon energy. That is why ultraviolet light burns skin and red light does not.