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Hydrogen is the lightest chemical element in the universe and is capable of bonding with other hydrogen atoms, forming a gas that has several uses

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Hydrogen is the chemical element with the smallest atomic mass (1 u) and the smallest atomic number (Z=1) among all the elements known to date. Despite being positioned in the first period of the IA family (alkali metals) of the Periodic Table, hydrogen does not have physical and chemical characteristics similar to the elements of this family and, therefore, is not part of it. Overall, hydrogen is the most abundant element in the entire universe and the fourth most abundant element on planet Earth.

Hydrogen has unique characteristics, that is, it does not resemble any other chemical element known to humans. Hydrogen commonly participates in the composition of several types of organic and inorganic substances, such as methane and water. When it is not part of chemical substances, it is found exclusively in gaseous form, whose formula is H2.

In its natural state and under normal conditions, hydrogen is a colorless, odorless and tasteless gas. It is a molecule with a great capacity to store energy and for this reason its use as a renewable source of electrical and thermal energy has been widely researched.

Discovery of hydrogen

In the middle of the 16th century, Pareselsvs decided to react some metals with acids, and ended up obtaining hydrogen. Although previously tested, Henry Cavendish managed to separate hydrogen from flammable gases and considered it a chemical element in 1766.

Not being a metal, much less a non-metal composes its peculiarity in the Periodic Table. In 1773, Antoine Lavoisier gave the chemical the name hydrogen, which derives from the Greek hydro and genes, and means water generator.

hydrogen in nature

• Hydrogen is part of the chemical composition of several organic substances (proteins, carbohydrates, vitamins and lipids) and inorganic (acids, bases, salts and hydrides);
• In atmospheric air, it is present in a gaseous form, represented by the molecular form H2, which forms through the covalent bond between two hydrogen atoms;
• Hydrogen also makes up water molecules, an important resource for life.

hydrogen sources

On Earth, hydrogen is not found in its purest form, but in its combined form (hydrocarbons and derivatives). For this reason, hydrogen must be extracted from various sources. The main sources of hydrogen are:

1. Natural gas;
2. Ethanol;
3. Methanol;
4. Water;
5. Biomass;
6. Methane;
7. Algae and Bacteria;
8. Gasoline and Diesel.

Atomic Hydrogen Characteristics

• It has three isotopes (atoms with the same atomic number and different mass numbers), namely protium (1H1), deuterium (1H2) and tritium (1H3);
• Features only one electronic level;
• It has a single proton at its core;
• It has only one electron at its electronic level;
• The number of neutrons depends on the isotope - protium (0 neutrons), deuterium (1 neutron) and tritium (2 neutrons);
• It has one of the smallest atomic radii on the Periodic Table;
• It has greater electronegativity than any metallic element;
• It has greater ionization potential than any metallic element;
• It is an atom capable of transforming into a cation (H+) or an anion (H-).

The stability of the hydrogen atom is achieved when it receives an electron in the valence shell (the outermost shell of an atom). In ionic bonds, hydrogen interacts exclusively with a metal, gaining an electron from it. In covalent bonds, hydrogen shares its electron with an ametal or with itself, forming single bonds.

Characteristics of molecular hydrogen (H2)

• At room temperature it is always found in a gaseous state;
• It is a flammable gas;
• Its melting point is -259.2°C;
• Its boiling point is -252.9°C;
• It has a molar mass equal to 2 g/mol, being the lightest gas;
• It presents a sigma covalent bond, type s-s, between the two hydrogen atoms involved;
• Between atoms, there is sharing of two electrons;
• It has linear type molecular geometry;
• Its molecules are non-polar;
• Its molecules interact through induced dipole forces.

Molecular hydrogen has great chemical affinity with several compounds. This property concerns the ability of a substance to react with another, because even if two or more substances are brought into contact, but there is no affinity between them, the reaction will not occur. In this way, it participates in reactions such as hydrogenation, combustion and simple exchange.

Ways of obtaining molecular hydrogen (H2)

physical method

Molecular hydrogen can be obtained from atmospheric air, as it is one of the gases present in this mixture. For this, it is necessary to submit the atmospheric air to the fractional liquefaction method and then to fractional distillation.

chemical method

Molecular hydrogen can be obtained through specific chemical reactions, such as:

• Simple exchange: reaction in which a non-noble metal (Me) displaces the hydrogen present in an inorganic acid (HX), forming any salt (MeX) and molecular hydrogen (H2):
• Me + HX → MeX + H2
• Hydration of coking coal (coal by-product): in this reaction the carbon (C) of the coal interacts with the oxygen in the water (H2O), forming carbon monoxide and the hydrogen gas:
• C + H2O → CO + H2
• Water electrolysis: when water is subjected to the electrolysis process, the formation of oxygen and hydrogen gases occurs:
• H2O(1) → H2(g) + O2(g)

Hydrogen Utilities

• Fuel for rockets or cars;
• Arc-flash torches (use electrical energy) to cut metals;
• Welds;
• Organic syntheses, more precisely in hydrocarbon hydrogenation reactions;
• Organic reactions that transform fats into vegetable oils;
• Production of hydrogen halides or hydrogenated acids;
• Production of metal hydrides such as sodium hydride (NaH).

Hydrogen bomb

The hydrogen bomb, H-bomb, or thermonuclear bomb is the atomic bomb that has the greatest potential for destruction. Its operation stems from a nuclear fusion process, which is why it can also be called a fusion bomb.

The explosion of a hydrogen bomb results from the fusion process, which takes place at very high temperatures, approximately 10 million degrees Celsius. The production process of this bomb begins with the union of hydrogen isotopes, called protium, deuterium and tritium. The junction of hydrogen isotopes makes the nucleus of the atom generate even more energy, because helium nuclei are formed, whose atomic mass is 4 times greater than that of hydrogen.

Thus, the core that was light becomes heavy. Therefore, the nuclear fusion process is thousands of times more violent than the fission one. The strength of a hydrogen bomb can reach 10 million tons of dynamite, releasing radioactive material and electromagnetic radiation at a level far superior to that of atomic bombs.

The first test of a hydrogen bomb, in 1952, released an amount of energy equivalent to about 10 million tons of TNT. It is noteworthy that this type of reaction is the energy source of stars like the Sun. It is composed of 73% hydrogen, 26% helium and 1% other elements. This is explained by the fact that fusion reactions take place in its nucleus, in which hydrogen atoms fuse to form helium atoms.

Fun Facts About Hydrogen

• Molecular hydrogen is lighter than air and was used in rigid airships by the German Count Ferdinand von Zeppelin, hence the name of the airships;
• Molecular hydrogen can be synthesized by some bacteria and algae;
• Hydrogen can be used in the production of clean energy fuel;
• Methane gas (CH4) is an increasingly important source of hydrogen.