Atom's structure

Hydrogen atom: properties, characteristics and use

Hydrogen atom: properties, characteristics and use

The hydrogen atom is of paramount importance in scientific study due to its fundamental role in understanding physics and chemistry.

Due to the simplicity of its atomic structure, it has been a key component in the development of atomic models and has helped lay the foundations of quantum theory.

Role of hydrogen in atomic models

In the Bohr atomic model, proposed by Niels Bohr in 1913, hydrogen played a central role. This model postulated that electrons orbit the nucleus in circular orbits and that only certain energy levels are allowed.

Bohr applied his model to the hydrogen atom and was able to derive a mathematical expression that explained the wavelengths of the spectral lines observed in the spectrum of hydrogen. These discoveries laid the foundations for quantum theory and the idea that energy is quantized in atoms.

Subsequently, the Schrödinger model of the atom, developed in the 1920s, used the wave equations to describe the probability distribution of the electron around the nucleus.

Although this model is more complex and based on quantum theory, it has also been and is applied to the hydrogen atom as a fundamental reference frame.

Hydrogen properties

Below we show some of the most outstanding properties of hydrogen atoms.

  1. Lightest element: The hydrogen atom is the lightest element on the periodic table with an atomic number of 1.

  2. Abundance: It is the most abundant element in the universe. On Earth it is found mainly in compounds such as water and hydrocarbons.

  3. Chemical Reactivity: It is highly reactive and can form covalent and ionic bonds with other elements. It is essential in many chemical reactions and is a key component in the formation of organic compounds.

  4. Isotopes: It has three main isotopes: protium (H-1), deuterium (H-2) and tritium (H-3). These isotopes have different numbers of neutrons in the nucleus, and therefore slightly different properties.

  5. State of aggregation: At room temperature and pressure, it is a colorless, odorless and highly flammable gas. However, at extremely low temperatures, it can exist in liquid or solid form.

  6. Electrical conductivity: Hydrogen is an electrical conductor when it is in the form of positive (protons) or negative (hydrides) ions.

  7. Energy: Hydrogen is a promising energy source, especially in the field of nuclear energy. Research on nuclear fusion is carried out using isotopes of hydrogen as fuel. Furthermore, it can be used as a fuel in fuel cells to produce electricity.

Hydrogen on the periodic table

On the periodic table, hydrogen is found at position number 1 and in group 1, due to its electronic configuration with a single electron in the K shell.

However, its location has been the subject of debate due to its unique chemical properties and its ability to lose or gain electrons under different conditions. Sometimes it is placed at the top of groups 1 and 17, or even considered a separate item.

The following table shows the properties of this chemical element in the periodic table:





Atomic number


Atomic mass


Electronic configuration

1s 1


1 (AI)





State of aggregation


Melting point

-259.16 °C

Boiling point

-252.87 °C


0.0899 g/ cm3


2.20 (Pauling scale)

Atomic radio

53 p.m.

ionic radius

137 p.m. (H + )

abbreviated electron configuration

[He] 2s 1

Isotopes of hydrogen

Hydrogen has three main isotopes, which are variants of the same atom with different numbers of neutrons in the nucleus. These isotopes are:

  1. Protium (H-1): Also known as common hydrogen, it is the most abundant and basic isotope of hydrogen. It consists of one proton in the nucleus and one electron in the orbit, making it an electrically neutral atom.

  2. Deuterium (H-2): It is an isotope of hydrogen that contains a proton and a neutron in the nucleus, which gives it a mass slightly greater than protium. Deuterium is stable and is found in small amounts in natural water, where it replaces a small percentage of the hydrogen atoms.

  3. Tritium (H-3): It is a radioactive isotope of hydrogen that contains one proton and two neutrons in the nucleus. Tritium is unstable and decays with a half-life of approximately 12.3 years. It is produced in the atmosphere by the action of cosmic rays and can also be generated artificially. Tritium is used in scientific, military and nuclear industry applications.

Fuel for nuclear fusion and electricity generation

The hydrogen atom plays a key role in nuclear fusion, which is a potentially powerful and clean source of energy.

Nuclear fusion is the process in which atomic nuclei combine to form a heavier nucleus, releasing a large amount of energy in the process according to Einstein's equation (E=mc2 ) .

Fusion reactions

Under the right conditions of extremely high temperature and pressure, hydrogen nuclei can fuse to form helium. This fusion can be done through two different processes:

  1. Proton-proton fusion: In this process, two hydrogen nuclei, each with one proton, combine to form a deuterium nucleus (an isotope of hydrogen with one proton and one neutron) releasing positrons, neutrinos, and a large amount of energy. in the form of gamma radiation.

  2. Deuterium-tritium fusion: In this process, a deuterium nucleus (with one proton and one neutron) and a tritium nucleus (with one proton and two neutrons) fuse to form a helium-4 nucleus, releasing one neutron, energy and gamma radiation.

Nuclear fusion in the Sun

Nuclear fusion is the source of energy that powers the sun and other stars, where enormous gravity and temperature allow this process to occur. However, replicating nuclear fusion on Earth to generate electricity has been challenging. 

The difficulty is maintaining the high temperatures and pressures necessary to keep the hydrogen plasma (a highly energetic state of matter) stable long enough for fusion to occur while consuming less energy than is obtained.

Investigation and development

Scientists have been researching and developing technologies to achieve controlled fusion in fusion reactors, such as the Tokamak and the Stellarator. These devices use magnetic fields and high temperatures to confine and heat hydrogen plasma, creating the conditions necessary for nuclear fusion.

Advantages of Nuclear Fusion

Nuclear fusion has several potential advantages over nuclear fission (heavy atom splitting).

  • By using hydrogen atoms as fuel, it could be considered a renewable energy source.

  • Fusion produces no long-lived nuclear waste, uses abundant fuels, and emits no greenhouse gases.

  • The amount of energy released in nuclear fusion is significantly higher than in nuclear fission.

Publication Date: May 25, 2023
Last Revision: May 25, 2023