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Hydrogen is normally found as a diatomic molecule. This means it has two hydrogen atoms in each molecule, which is why pure hydrogen is denoted as ‘H2’.
Hydrogen is a diatomic molecule-forming element. Diatomic molecules are made up of two atoms of the same element. They usually exist because the element is too reactive to connect to another atom. Many of hydrogen’s unusual features are due to its reactivity.
Physical Properties of Hydrogen
Physical properties of hydrogen include things like its density of 0.0000899 g/cm, which can be observed or measured. Hydrogen has a melting point of -259.2 °C and a boiling point of -252.8 °C. It is a colourless gas that is so much lighter than air that it can escape the earth’s gravitational attraction and fly into space. The first element on the periodic table, hydrogen, has only one proton and one electron. It has no neutrons.
Hydrogen exists in two different spin isomers of hydrogen diatomic molecules (called orthohydrogen and parahydrogen), which differ in their nuclei’s relative spin. The orthohydrogen form’s spins are parallel, while the parahydrogen form’s spins are antiparallel. Hydrogen gas is 75% orthohydrogen and 25% parahydrogen at standard temperature and pressure. It comes in a variety of forms, including compressed gaseous hydrogen, liquid hydrogen, slush hydrogen (a mixture of liquid and solid), and solid and metallic forms.
Many of the chemical properties of hyd
rogen, such as its proclivity for forming covalent bonds with oxidising elements, are due to its small size.
Some Chemical Properties of Hydrogen
When hydrogen comes into touch with oxygen, it becomes extremely flammable. It is a non-metallic element that behaves similarly to metals in some bonding circumstances. In an ionic compound, hydrogen can donate electrons to the non-metal it bonds with, or it can act as a non-metal in a molecular molecule, sharing electrons with another atom. Hydrogen’s electronegativity is relatively strong, which adds to its bonding affinity and diatomic nature.
There are multiple chemical properties of hydrogen that influence how it is used as a fuel:
It mixes with oxygen to create water, which is essential for life on this planet.
It has a high energy density per volume (almost three times that of gasoline) but a low energy density per weight at standard temperature and pressure. The volumetric energy density of hydrogen can be improved by storing it under higher pressure or at extremely low temperatures as a liquid. Metal hydrides can also be adsorbed with hydrogen.
Hydrogen is extremely flammable, requiring only a minimal amount of energy to ignite and burn. It also has a wide flammability range, which means it can burn when it accounts for 4 to 74% of the air volume.
Because hydrogen has a pale-blue, almost-invisible flame, its fires are difficult to spot.
The burning of hydrogen produces no carbon dioxide (CO2), particulate matter, or sulphur. Under some circumstances, it can emit nitrous oxide (NOX).
Hydrogen can be made from renewable resources, such as ethanol reformation (which produces some carbon dioxide) and water electrolysis (electrolysis is very expensive).
Hydrogen Bonding
Hydrogen participates in hydrogen bonding, which is a unique set of circumstances. A hydrogen bond is an attraction between two molecules in which the proton in one molecule’s hydrogen atom attracts unbonded pairs of electrons in another molecule. In water, for example, strong hydrogen bonding occurs when the hydrogen atoms of one molecule are attracted to the oxygen atom of another. Water molecules are held together by this intermolecular force, which also explains why water has such a high surface tension.
Hydrogen Isotopes
1H, 2H, and 3H are the three forms of isotopes of hydrogen that exist in nature. Protium is the formal term for 1H, which occurs in 99.98% abundance. Deuterium (mass number = 2) is a chemical element with one electron, one proton, and one neutron. Deuterium and its compounds are used as non-radioactive labels in chemical research and as solvents for 1H-NMR spectroscopy. Tritium (mass number = 3) is made up of one proton, two neutrons, and one electron. It is radioactive and has a half-life of 12.32 years before decaying into helium-3 via beta decay. For more information, refer to the isotopes of hydrogen notes in detail!
Conclusion
Hydrogen is the most plentiful element in the universe, accounting for 90% of its total mass. It has been used safely in large quantities in chemical and metallurgical applications, the food industry, and the space programme for many years. As hydrogen and fuel cells become more important in addressing our country’s and the world’s energy needs, it’s critical to reduce the risks associated with using hydrogen as a fuel.
