Exploring the Characteristics of Hydrogen: Properties, Origin, and Uses


Discover the fascinating world of hydrogen – the first element of the periodic table, its atomic properties, physical characteristics, and the origin of its name. Learn about its high flammability, limited solubility, abundance in the universe, isotopes, and diverse industrial applications, along with associated risks.

Exploring the Characteristics of Hydrogen

Hydrogen is the first element of the periodic table and the most abundant of the known universe: it constitutes more than three quarters of all observable matter. It is a light element, with the simplest known atomic form, and usually appears as a colorless, odorless and flammable monoatomic gas.

Who discovered hydrogen?

He was the British physicist and chemist Henry Cavendish in 1766 and forms the bulk of the mass of stars in its initial phase. Our Sun, in fact, is a huge hydrogen fusion bomb in space. Hydrogen, according to experts, would have been the first element to be constituted of all and is indispensable for the formation of water (H2O).

Today, hydrogen is produced industrially and used in numerous applications, from the refinement of fossil fuels to welding and cryogenics. Below we expose its most important characteristics.


Characteristics Of Hydrogen

1. Atomic properties

Hydrogen is the simplest and most abundant element in the universe, making up about 75% of its elemental mass. Here are some key atomic properties of hydrogen:

  1. Atomic Number (Z): Hydrogen has an atomic number of 1, which means it has 1 proton in its nucleus. This is what defines it as hydrogen.
  2. Atomic Mass: The most common isotope of hydrogen, protium, has an atomic mass of approximately 1.00784 atomic mass units (u).
  3. Electron Configuration: The electron configuration of hydrogen is 1s^1, meaning it has one electron in its 1s orbital.
  4. Isotopes: Hydrogen has three naturally occurring isotopes: protium (^1H), deuterium (^2H or D), and tritium (^3H or T). Protium is by far the most common, making up about 99.98% of natural hydrogen. Deuterium is stable and makes up about 0.02%, while tritium is radioactive with a half-life of about 12.32 years.
  5. Size: Hydrogen is the smallest and lightest element. It has the smallest atomic radius of all the elements because it has only one proton in its nucleus, giving it a very compact structure.
  6. Ionization Energy: The ionization energy of hydrogen is relatively low compared to most elements. It takes just 1312 kJ/mol to remove the outermost electron from a hydrogen atom in the gas phase.
  7. Electronegativity: Hydrogen has an electronegativity value of 2.20 on the Pauling scale, making it moderately electronegative. This means it tends to attract electrons, though not as strongly as elements like oxygen or fluorine.
  8. Bonding: Hydrogen can form a variety of compounds due to its ability to either gain or lose an electron. It can form covalent bonds, such as in H2 (hydrogen gas), or ionic bonds, such as in hydrides like NaH (sodium hydride).
  9. Diatomic Form: In its most common form, hydrogen exists as H2, a diatomic molecule. This diatomic form is the most stable state of hydrogen under normal conditions.

These properties contribute to hydrogen’s unique role in chemistry and physics. Its simplicity and versatility make it a crucial element in a wide range of applications, from fuel sources to industrial processes and even in biological systems.

2. Physical properties

Hydrogen, the lightest and most abundant element in the universe, has several important physical properties:

  1. Phase at Room Temperature: Hydrogen is a colorless, odorless, and tasteless gas at room temperature and pressure. Its boiling point is -252.87°C (-423.17°F), and its melting point is -259.2°C (-434.6°F).
  2. Density: Hydrogen gas has a very low density, about 0.08988 grams per cubic centimeter (g/cm³) at 0°C and 1 atmosphere of pressure. This makes it much lighter than air.
  3. Solubility: Hydrogen is sparingly soluble in water. At room temperature and pressure, the solubility of hydrogen gas in water is about 0.0016 g/L.
  4. Heat Capacity: The specific heat capacity of hydrogen gas is relatively low compared to other substances, at about 14.267 J/g°C. This means it requires relatively little energy to change its temperature.
  5. Thermal Conductivity: Hydrogen has a high thermal conductivity, which means it can transfer heat very effectively. This property makes it useful in various industrial applications, including cooling systems.
  6. Viscosity: Hydrogen gas has a very low viscosity, which means it flows easily. This property is important for its use in various industrial processes, including rocket propulsion.
  7. Flammability: Hydrogen is highly flammable in its gaseous form, forming a highly explosive mixture when combined with air. It has a wide flammability range between 4% and 75% in air.
  8. Boiling and Freezing Points: Hydrogen has the lowest boiling and freezing points of all the elements. Its boiling point is -252.87°C (-423.17°F), and its freezing point is -259.2°C (-434.6°F).
  9. Critical Point: Hydrogen has a critical point at 33 K (-240.17°C or -400.3°F) and 1.29 MPa, above which it cannot exist as a liquid regardless of pressure.
  10. Molar Mass: The molar mass of hydrogen gas is about 2.016 g/mol.
  11. Expansivity: Hydrogen gas expands greatly when heated, contributing to its use as a lifting gas in airships and balloons historically.

These physical properties of hydrogen are crucial for understanding its behavior and applications in various industries, including fuel cells, aerospace, metallurgy, and more.

3. Origin of the name

The name “hydrogen” is derived from the Greek words “hydro” which means “water” and “genes” which means “forming” or “producing.” When combined, “hydrogen” literally translates to “water-forming” or “water-producing.” This name is very fitting because hydrogen was first recognized for its role in forming water.

When hydrogen reacts with oxygen, it forms water (H2O). The chemical equation for this reaction is:

  • 2H2 + O2 -> 2H2O

This equation shows that two molecules of hydrogen (H2) combine with one molecule of oxygen (O2) to produce two molecules of water (H2O). This is a crucial reaction not only in chemistry but also in biology, as water is essential for life as we know it.


So, the name “hydrogen” reflects its fundamental role in the creation of water. This element’s ability to combine with oxygen to produce water is one of its most important and defining characteristics, making the name quite fitting.

4. Symbol

Hydrogen is the first element of the Periodic Table, always located in the upper left corner, above Lithium. It is represented by the symbol H. It should be noted that hydrogen does not have characteristics that make it easily classifiable in the groups of the Table, so it is almost always its own group. However, it is usually included in family IA (Group 1)


5. Inflammability

Hydrogen is highly flammable. Here are some characteristics related to its inflammability:

  1. Flammability: Hydrogen is one of the most flammable substances known. It has a very low ignition energy, which means it can ignite easily. Even a small spark or a slight increase in temperature can cause hydrogen to burn.
  2. Wide Flammability Range: Hydrogen has a wide flammability range. It can burn in a concentration range of about 4% to 75% in air. This wide range makes it potentially more dangerous because it can ignite at relatively low concentrations.
  3. Invisible Flame: When hydrogen burns, the flame is nearly invisible to the naked eye, especially in daylight. This can be a safety hazard because the flame might not be immediately noticeable.
  4. High Flame Speed: The flame speed of hydrogen is very high, which means that fires involving hydrogen can spread rapidly.
  5. Non-toxic Combustion: When hydrogen burns, it produces only water vapor (H2O) and heat. Unlike some other fuels, hydrogen combustion does not produce toxic byproducts, which is an advantage in certain applications.

Because of its high flammability, handling and storing hydrogen safely is critical. Precautions such as proper ventilation, avoiding sources of ignition, and using appropriate storage containers are essential when working with hydrogen. Despite its flammability, hydrogen is a valuable resource in many applications, including fuel cells for clean energy production, rocket propulsion, and industrial processes.

6. Solubility

Hydrogen’s solubility depends on the substance it is interacting with. Here are some aspects of hydrogen’s solubility:

  1. Solubility in Water: Hydrogen is sparingly soluble in water. At room temperature and pressure, only a small amount of hydrogen gas will dissolve in water. The solubility of hydrogen in water is about 0.0016 g/L at 20°C and 1 atm pressure.
  2. Solubility in Organic Solvents: Hydrogen is more soluble in some organic solvents compared to water. For example, it is more soluble in alcohols like ethanol or methanol than in water. This solubility varies depending on factors such as temperature and pressure.
  3. Hydrogenation Reactions: Hydrogen is often used in hydrogenation reactions in organic chemistry. In these reactions, hydrogen can dissolve into certain organic compounds to facilitate reactions, such as the conversion of alkenes to alkanes in the presence of a catalyst.
  4. Metal Hydrides: Hydrogen can form compounds known as metal hydrides, where hydrogen atoms are bonded to metals. These metal hydrides often have different solubility properties compared to pure hydrogen gas. For example, some metal hydrides can absorb large amounts of hydrogen gas, making them useful for hydrogen storage.

In summary, hydrogen’s solubility is generally low in water but can vary in other solvents and when forming compounds with certain metals. Its solubility properties are important in various industrial and chemical processes, including its role in hydrogenation reactions and hydrogen storage technologies.

7. Abundance

Where is hydrogen? As we have said, hydrogen constitutes more than 70% of the visible matter of the universe, so it is the most abundant element of all.

It can be found in its pure state in the heart of young stars, in the atmosphere of large gaseous planets (such as Jupiter and Venus), as traces on the Earth’s surface and also as part of thousands of organic and inorganic compounds in nature. . Many biological processes throw it as a result.

8. Isotopes

Hydrogen has several isotopes (atomic variants):

  • Protium Composed of a proton and no neutron in its nucleus, it has positive electric charge. It is the most common version of hydrogen.
  • Deuterium. Heavier than ordinary hydrogen, it has a neutron next to the proton in its nucleus.
    Triad It has two neutrons in its nucleus next to the proton, so it’s even heavier.

9. Uses and applications

What is hydrogen for? This chemical element is part of a wide range of industries, both in applied chemistry (hydrocarbons, fertilizers, space fuels), physics (controlled fusion of hydrogen to generate electricity), and in other areas such as pharmacology, transportation (balloons aerostatic and zeppelins), and semiconductors.


10 Characteristics Of Hydrogen - What is Hydrogen?

10. Risks

The handling of hydrogen in its pure state is extremely delicate, since its flammability represents an important industrial risk, as well as its ability to mechanically suffocate by displacing oxygen from the air. Liquid hydrogen, a powerful cooler, can also destroy organic tissues.

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