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By calculating its wavelength (in nm), show that the second line in the Lyman series is UV radiation.

User Oleshko
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Answer:

λ = 102.78 nm

This radiation is in the UV range,

Step-by-step explanation:

Bohr's atomic model for the hydrogen atom states that the energy is

E = - 13.606 / n²

where 13.606 eV is the ground state energy and n is an integer

an atom transition is the jump of an electron from an initial state to a final state of lesser emergy

ΔE = 13.606 (1 /
n_(f)^(2) - 1 / n_{i}^{2})

the so-called Lyman series occurs when the final state nf = 1, so the second line occurs when ni = 3, let's calculate the energy of the emitted photon

DE = 13.606 (1/1 - 1/3²)

DE = 12.094 eV

let's reduce the energy to the SI system

DE = 12.094 eV (1.6 10⁻¹⁹ J / 1 ev) = 10.35 10⁻¹⁹ J

let's find the wavelength is this energy, let's use Planck's equation to find the frequency

E = h f

f = E / h

f = 19.35 10⁻¹⁹ / 6.63 10⁻³⁴

f = 2.9186 10¹⁵ Hz

now we can look up the wavelength

c = λ f

λ = c / f

λ = 3 10⁸ / 2.9186 10¹⁵

λ = 1.0278 10⁻⁷ m

let's reduce to nm

λ = 102.78 nm

This radiation is in the UV range, which occurs for wavelengths less than 400 nm.

User Chux Uzoeto
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