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Hydrogen. Atom, molecule and properties

16/04/2026

The online hydrogen simulations on this page will help you learn about his very important element of nature. We will discover what the atomic structure of hydrogen is like and we will see the atomic model of hydrogen. We will also learn what the hydrogen molecule looks like and some of its most important properties and characteristics

This Thematic Unit is part of our Chemistry collection

STEM OnLine mini dictionary

Deuterium

Stable isotope of hydrogen containing one proton and one neutron in its nucleus.

Diatomic Gas

Molecule formed by two atoms of the same element, as occurs with elemental hydrogen in nature.

Hydride

Chemical compound formed by the combination of hydrogen with any other element, whether metallic or non-metallic.

Hydrogen

Chemical element with atomic number 1, the lightest in the periodic table, which under normal conditions occurs as a diatomic gas (H₂).

Isotope

Atoms of the same element with the same number of protons but a different number of neutrons. Hydrogen has three: protium, deuterium, and tritium.

Tritium

Radioactive isotope of hydrogen whose nucleus consists of one proton and two neutrons.

What is hydrogen

Hydrogen is a chemical element with an atomic number of 1, which means that it has a single proton in its nucleus and a single electron in its valence shell. In its molecular form, hydrogen is in the form of H2, which consists of two hydrogen atoms joined by a covalent bond. It is a diatomic molecule, two atoms of the same element bonding together to form a molecule.

Hydrogen atom. Atomic model of hydrogen

The hydrogen atom, the simplest atom in the universe, has been essential to the development of atomic theory. With a nucleus consisting of only one proton and one electron orbiting around it, the atomic model of hydrogen has served as the basis for understanding the structure of atoms in general. From Bohr’s model, which describes the electron moving in discrete energy levels, to modern models based on quantum mechanics, the study of hydrogen has illuminated the fundamental principles of chemistry and physics. Experiments such as light scattering on the hydrogen atom have been crucial in validating these theories, allowing us to explore the most intriguing properties of this essential element.

Hydrogen molecule

The hydrogen molecule, represented as H2, is one of the simplest and most essential molecules in nature. It is made up of two hydrogen atoms that share a pair of electrons, creating a covalent bond that holds them together. This bonding allows them to achieve a more stable electronic configuration, making molecular hydrogen a key element in countless chemical and biological processes. In addition, its diatomic structure and unique properties make it a fundamental component in the study of the behavior of gases and in various technological applications.

Properties of hydrogen

Hydrogen is the lightest and most abundant element in the universe. Under standard conditions of temperature and pressure, it is a colorless, odorless and highly flammable gas. It is highly reactive and can form bonds with many other elements, including carbon, nitrogen, oxygen and halogens.

Chemical relevance

Hydrogen is an important element in organic chemistry, as it is a key component of hydrocarbon molecules, which form the basis of fossil fuels. It is part of the water molecule (H2O) and other chemical compounds essential to life. Its ability to form compounds with different elements makes it a key intermediate in many industrial chemical reactions, such as the production of ammonia by the Haber-Bosch process.

Physical properties

In terms of physical properties, hydrogen has a very low boiling point (-252.87°C) and an even lower melting point (-259.16°C). Although it is a gas at normal temperature and pressure, it can be liquefied at extremely low temperatures and stored in liquid form for use in industrial and transportation applications. It should be noted that hydrogen has a very low density, which makes it difficult to store and transport efficiently, but at the same time makes it ideal for applications such as research balloons and space rockets.

Thermal capacity and conductivity

Hydrogen is an excellent conductor of heat and electricity and has a high heat capacity. This makes it an attractive energy medium in advanced heat transfer systems. In addition, its low viscosity and high diffusion make it ideal for applications in fuel cell technology.

Hydrogen isotopes

A unique property of hydrogen is the existence of its three isotopes: protium, deuterium and tritium. Protium is the most common isotope, while deuterium is used in applications such as nuclear reactors and fusion research. Tritium, although radioactive, plays a key role in nuclear fusion experiments and in the illumination of night vision devices.

Taken together, all these properties make hydrogen both scientifically and technologically exciting, with applications ranging from basic research to the development of sustainable energy solutions.

STEM OnLine mini dictionary

Deuterium

Stable isotope of hydrogen containing one proton and one neutron in its nucleus.

Diatomic Gas

Molecule formed by two atoms of the same element, as occurs with elemental hydrogen in nature.

Hydride

Chemical compound formed by the combination of hydrogen with any other element, whether metallic or non-metallic.

Hydrogen

Chemical element with atomic number 1, the lightest in the periodic table, which under normal conditions occurs as a diatomic gas (H₂).

Isotope

Atoms of the same element with the same number of protons but a different number of neutrons. Hydrogen has three: protium, deuterium, and tritium.

Tritium

Radioactive isotope of hydrogen whose nucleus consists of one proton and two neutrons.

Explore the exciting STEM world with our free, online, simulations and accompanying companion courses! With them you’ll be able to experience and learn hands-on. Take this opportunity to immerse yourself in virtual experiences while advancing your education – awaken your scientific curiosity and discover all that the STEM world has to offer!

Atomic model of hydrogen


How do scientists determine the structure of atoms, without looking at them? Test the different models by shooting light at the atom. See how the atomic model of hydrogen prediction matches the experimental results.


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Hydrogen molecule


Hydrogen is the chemical element of atomic number 1, represented by the symbol H. It usually occurs in its molecular form. , The hydrogen molecule is made up of two hydrogen atoms, which gives rise to the diatomic gas H2 under normal conditions. This gas is flammable, colorless, odorless, non-metallic and insoluble in water.


Hydrogen


H2
Hydrogen
SingleBondSingle bond
DoubleBond
Double bond
TripleBondTriple bond
WedgeBond
Wedge bond
HashBond
Hash bond

Models of the hydrogen atom


How do scientists determine the structure of atoms, without looking at them? Test the different models by shooting light at the atom. See how the model prediction matches the experimental results.

Screen too narrow

This Java simulation cannot run on this device because it has a screen that is too narrow. We recommend that, for a better user experience, you run it on a device with a wider screen.

Narrow screen

Although this Java simulation can be run on your device, we recommend that for the better user experience, you run it on a device with a wider screen.


Licencia de Creative Commons

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Test your knowledge

Hydrogen is the simplest and most abundant chemical element in the universe. It has atomic number 1, meaning its atom consists of a single proton in the nucleus and one electron in its outer shell. This simplicity makes it a fundamental model for the development of atomic theory. In its molecular form, hydrogen appears as H₂, a diatomic molecule formed by two atoms joined through a covalent bond. This molecule is stable and participates in numerous chemical and biological processes. The study of hydrogen has been key to understanding concepts such as energy levels, atomic spectra and gas behavior. Its reactivity and ability to form compounds with many elements make it essential in organic, inorganic and industrial chemistry.
The hydrogen atom has been fundamental to the development of atomic theory due to its extremely simple structure: one proton in the nucleus and one electron orbiting around it. Bohr’s model used hydrogen to explain that electrons move in discrete energy levels, allowing interpretation of its emission spectrum. Later, quantum mechanics refined this view through wave functions and orbitals, describing electron behavior more accurately. Experiments such as light scattering and spectroscopic analysis of hydrogen validated these theories and helped explain phenomena like energy quantization and electronic structure. Thanks to hydrogen, principles were established that now support modern chemistry, quantum physics and the study of more complex atoms.
The hydrogen molecule H₂ is important because it is one of the simplest and most stable molecules that exist. It is formed by two atoms that share a pair of electrons, allowing them to reach a more stable configuration. This molecule participates in essential chemical reactions, from biological processes to industrial applications. Hydrogen gas is also key for studying gas behavior and understanding how covalent bonds work. In addition, it is an important candidate as a clean fuel, since burning it produces only water.
Hydrogen is a colorless, odorless and very light gas. It is highly flammable and reacts with many elements, such as oxygen, nitrogen and halogens. It has extremely low melting and boiling points, meaning it can only be liquefied at very cold temperatures. It also has very low density and high heat capacity, making it an excellent conductor of heat. These properties explain its use in balloons, rockets, fuel cells and industrial processes.
Hydrogen is used in ammonia production, petroleum refining, fuel cells and as an industrial gas. It is also part of water and many essential compounds for life. Today it is especially relevant because it is being studied as a clean fuel: when used for energy, it produces only water and does not generate carbon dioxide. It can also be produced from renewable energy sources, making it a promising option for reducing dependence on fossil fuels and moving toward sustainable energy systems.

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