Question 1

Paper 2Medium7 marks

A gas is examined using an emission spectrum and an absorption spectrum. The absorption spectrum is recorded after continuous light passes through a cooler sample of the same gas. Figure 1 shows measured relative intensities for both spectra.

For calculations, use h=6.63×10−34 J sh=6.63\times10^{-34}\,\text{J s} and c=3.00×108 m s−1c=3.00\times10^8\,\text{m s}^{-1}

Emission spectrumAbsorption spectrum1.00.90.80.70.60.50.40.30.20.10.01.00.90.80.70.60.50.40.30.20.10.0400450500550600650670Relative emissionintensity /arbitrary unitsRelative absorptionintensity /arbitrary unitswavelength / nm
(a)

Read Figure 1 to state the wavelengths of the shortest- and longest-wavelength emission lines. Give your answers in nm.

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(b)

Determine the energy of a photon in the longest-wavelength emission line. Give your answer in J.

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(c)

Explain what the matching emission and absorption line positions indicate about atomic energy levels.

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(d)

A nucleus of the element contains 12 protons and 13 neutrons. Write its nuclear notation, using XX for the chemical symbol.

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