Questions: A hydrogen atom exists with its electron in the n=4 state. The electron undergoes a transition to the n=3 state. Calculate a. The energy of the photon emitted in Joules (J) b. Its frequency in Hz c. Its wavelength in nanometers (nm).

A hydrogen atom exists with its electron in the n=4 state. The electron undergoes a transition to the n=3 state. Calculate
a. The energy of the photon emitted in Joules (J)
b. Its frequency in Hz
c. Its wavelength in nanometers (nm).
Transcript text: 5. A hydrogen atom exists with its electron in the $n=4$ state. The electron undergoes a transition to the $n=3$ state. Calculate a. The energy of the photon emitted in Joules (J) b. Its frequency in Hz ) c. Its wavelength in nanometers ( nm ). (See Example Problem 2.3 on page 47 )
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Solution

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Solution Steps

Step 1: Calculate the Energy Levels

The energy levels of a hydrogen atom are given by the formula: \[ E_n = -\frac{13.6 \, \text{eV}}{n^2} \]

For \( n = 4 \): \[ E_4 = -\frac{13.6 \, \text{eV}}{4^2} = -\frac{13.6 \, \text{eV}}{16} = -0.85 \, \text{eV} \]

For \( n = 3 \): \[ E_3 = -\frac{13.6 \, \text{eV}}{3^2} = -\frac{13.6 \, \text{eV}}{9} = -1.5111 \, \text{eV} \]

Step 2: Calculate the Energy of the Photon Emitted

The energy of the photon emitted during the transition from \( n = 4 \) to \( n = 3 \) is the difference in energy levels: \[ \Delta E = E_3 - E_4 = -1.5111 \, \text{eV} - (-0.85 \, \text{eV}) = -1.5111 \, \text{eV} + 0.85 \, \text{eV} = -0.6611 \, \text{eV} \]

Convert the energy from electron volts to joules: \[ 1 \, \text{eV} = 1.6022 \times 10^{-19} \, \text{J} \] \[ \Delta E = -0.6611 \, \text{eV} \times 1.6022 \times 10^{-19} \, \text{J/eV} = -1.0588 \times 10^{-19} \, \text{J} \]

Since energy is emitted, we take the absolute value: \[ \Delta E = 1.0588 \times 10^{-19} \, \text{J} \]

\(\boxed{\Delta E = 1.0588 \times 10^{-19} \, \text{J}}\)

Step 3: Calculate the Frequency of the Photon

The frequency \( \nu \) of the photon can be found using the relation: \[ E = h \nu \] where \( h \) is Planck's constant (\( h = 6.6261 \times 10^{-34} \, \text{J} \cdot \text{s} \)).

\[ \nu = \frac{E}{h} = \frac{1.0588 \times 10^{-19} \, \text{J}}{6.6261 \times 10^{-34} \, \text{J} \cdot \text{s}} = 1.597 \times 10^{14} \, \text{Hz} \]

\(\boxed{\nu = 1.597 \times 10^{14} \, \text{Hz}}\)

Step 4: Calculate the Wavelength of the Photon

The wavelength \( \lambda \) of the photon can be found using the speed of light \( c \) and the frequency \( \nu \): \[ \lambda = \frac{c}{\nu} \] where \( c = 3.00 \times 10^8 \, \text{m/s} \).

\[ \lambda = \frac{3.00 \times 10^8 \, \text{m/s}}{1.597 \times 10^{14} \, \text{Hz}} = 1.878 \times 10^{-6} \, \text{m} \]

Convert the wavelength from meters to nanometers: \[ 1 \, \text{m} = 10^9 \, \text{nm} \] \[ \lambda = 1.878 \times 10^{-6} \, \text{m} \times 10^9 \, \text{nm/m} = 1878 \, \text{nm} \]

\(\boxed{\lambda = 1878 \, \text{nm}}\)

Final Answer

a. The energy of the photon emitted in Joules (J) is \(\boxed{1.0588 \times 10^{-19} \, \text{J}}\).

b. Its frequency in Hz is \(\boxed{1.597 \times 10^{14} \, \text{Hz}}\).

c. Its wavelength in nanometers (nm) is \(\boxed{1878 \, \text{nm}}\).

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