The Hydrogen Spectrum: A Window to the Atom and the Energy Future

What is the hydrogen spectrum?

Imagine visible light as a rainbow. If we analyze the light emitted or absorbed by a hydrogen atom, instead of seeing a continuous rainbow, we will see a series of lines of specific colors. This set of lines is what we call the hydrogen spectrum .

Why do we see lines and not a complete rainbow?

This is due to the quantum nature of the atom. Electrons in a hydrogen atom can only occupy certain discrete energy levels. When an electron jumps from a higher energy level to a lower one, it emits a photon of light with a specific energy, corresponding to a particular color. Similarly, when an electron absorbs a photon of the right energy, it can jump to a higher energy level.

These lines are unique to hydrogen and act as its “fingerprint.” But it is not just a visual phenomenon: hydrogen’s spectral properties have practical applications, such as identifying its purity, a key aspect in the production of green hydrogen for energy use.

The hydrogen spectrum has also allowed us to better understand atomic structure and continues to help us develop technologies such as electrolysers, which split water molecules into oxygen and hydrogen using renewable electricity.

Emission spectrum vs. absorption spectrum

• Emission spectrum: This occurs when the electrons of an excited atom (for example, by heating) return to their ground state, emitting photons of light. In the emission spectrum of hydrogen, we see the bright lines corresponding to the frequencies of the emitted photons.
• Absorption spectrum: This occurs when white light passes through a hydrogen gas. The hydrogen electrons absorb photons of certain frequencies, corresponding to the allowed transitions, leaving dark lines in the continuous spectrum.

Why is the emission spectrum of hydrogen not continuous?

The discontinuity of the hydrogen emission spectrum is irrefutable proof of the quantum nature of the atom. If electrons could have any energy value, the spectrum would be continuous. However, the energy levels in the hydrogen atom are quantized, meaning they only have specific values.

How to calculate the emission spectrum of hydrogen?

To calculate the frequencies of the spectral lines of hydrogen, the Rydberg formula is used:

1/λ = R_H (1/n₁² - 1/n₂²)
        

Where:

• λ is the wavelength of the emitted light
• R_H is the Rydberg constant
• n₁ and n₂ are integers representing the initial and final energy levels of the electron

Who is limited to explaining the emission spectrum of hydrogen?

The Bohr atomic model was one of the first attempts to explain the emission spectrum of hydrogen. Although successful for hydrogen, it could not explain the spectra of more complex atoms. Quantum mechanics, developed by Schrödinger and others, provided a more accurate and complete description of the atom and its spectrum.

Applications of the hydrogen spectrum

The study of the hydrogen spectrum has been fundamental in the development of quantum mechanics and has had numerous applications in fields such as:

• Astrophysics: Analysis of the spectra of stars allows us to determine their chemical composition and temperature.
• Analytical chemistry: Spectroscopy is used to identify unknown substances.
• Lasers: The stimulated emission principle, based on electronic transitions, is fundamental to the operation of lasers.

In summary, the hydrogen spectrum is a powerful tool for understanding the structure of matter at the atomic level. Its study has revolutionized our understanding of the universe and continues to be an active area of research.

From Quantum Physics to Green Energy

We have explored how the hydrogen spectrum reveals the secrets of atomic structure. But beyond quantum physics, hydrogen, the simplest and most abundant element in the universe, is playing an increasingly important role in our quest for a sustainable energy future.

Green Hydrogen: The Protagonist of the Energy Future

Green hydrogen, produced from the electrolysis of water using renewable energy, is presented as a promising solution to decarbonize sectors that are difficult to electrify, such as heavy industry and transport.

• Why green hydrogen? Its combustion produces only water vapour, making it a clean fuel with no direct CO2 emissions. In addition, it can be stored and transported, offering greater flexibility compared to other renewable energy sources.
• The hydrogen spectrum and green hydrogen production: Although it may seem like a distant connection, understanding the hydrogen spectrum is critical to developing more efficient hydrogen production technologies. For example, studying electronic transitions in the hydrogen atom helps us design more efficient catalysts for water electrolysis.

The Hydrogen Spectrum and Hydrogen Detection

Spectroscopy, the science of the interaction of electromagnetic radiation with matter, is widely used to detect and quantify hydrogen. In the production of green hydrogen, infrared spectroscopy is used to monitor the purity of the hydrogen produced and detect potential contaminants.

The Future of Hydrogen and the Atomic Spectrum

A deep understanding of the hydrogen spectrum and other elements remains essential to advance the development of green hydrogen-related technologies:

• Development of new materials: The study of atomic spectra helps us design new materials with specific optical and electronic properties, such as catalysts used in fuel cells.
• Process optimization: Spectroscopy allows real-time monitoring of hydrogen production and storage processes, which in turn facilitates the optimization of these processes.
• Leak detection: Detecting hydrogen leaks is crucial to ensuring safety in production and storage facilities. Infrared spectroscopy is a valuable tool for this task.

Conclusion?

In conclusion, the hydrogen spectrum, although it seems like an abstract concept of quantum physics, has a very practical application in the development of clean and sustainable energy technologies. By understanding the interaction of light with the hydrogen atom, we can move towards a cleaner and more efficient energy future.