What is Hydrogen

A chemical element with the symbol H and atomic number 1 is called hydrogen. It is the most abundant and lightest element of the universe. It makes up about 75% of its elemental mass. In the purest state of hydrogen, it has no odor, taste, or color. It is highly reactive and forms compounds with most other elements.

There are multiple uses of hydrogen such as a fuel for hydrogen fuel cells, a reducing agent in manufacturing, a coolant in power plants, and a fuel for rockets. Petroleum is cleaned by using hydrogen, it is also used to make methanol with other chemicals, and ammonia which is used in fertilizers.

Hydrogen Symbol

The symbol for Hydrogen originated from its name, which comes from the Greek words hydro and genes, which means water-forming. It reflects the fact that Hydrogen combines with oxygen to make water H₂O. The symbol “H” represents Hydrogen in the periodic table of elements and chemical equations. The letter “H” was chosen because it is the first letter of the element’s name. The symbol is always capitalized and typically appears in subscripts when representing the atomic number or mass of an atom or molecule of Hydrogen.

Position of Hydrogen in Periodic Table

It is a non-metal and the lightest element in the periodic table. The place of hydrogen in the periodic table is controversial because it has some remarkable features that do not fit neatly into any one group or category. It is often placed at the top of group 1, above lithium, because it has one electron in its outermost shell and similar chemical properties to the alkali metals.

However, hydrogen also shares some properties with halogens and can form positive and negative ions, unlike alkali metals. Some periodic tables place hydrogen in a separate group, while others place it in groups 17 or 18. The position of hydrogen in the periodic table remains a topic of debate among chemists and educators.

Atomic Hydrogen

Atomic hydrogen refers to the state of hydrogen in which the hydrogen atoms are in their ground state, meaning that they have a single electron in their lowest energy level (also known as the 1s orbital). Atomic hydrogen is a highly reactive species that can participate in various chemical reactions, particularly radical chemistry. It is a stronger Reducing Agent than molecular Hydrogen.

It can be produced through various methods, including dissociating hydrogen molecules using high-energy radiation or chemical reactions that generate hydrogen radicals. It is also an essential intermediate in many chemical reactions, particularly in the combustion of fuels and in atmospheric chemistry. It is a crucial feature of plasma. Atomic hydrogen can be ionized in plasma to create hydrogen plasma, which has a variety of uses, such as semiconductor devices and some kinds of lighting.

Molecular Hydrogen

Molecular hydrogen also called diatomic hydrogen or H₂ is the simplest and lightest molecule. It consists of two hydrogen atoms connected together via covalent bond. It is odorless, colorless & tasteless gas that is highly combustible and explosive.

• Chemical formula: H₂
• Molecular weight: 2.016 g/mol
• Density: 0.08988 g/L
• Boiling point: -252.87 °C (-423.17 °F)
• Melting point: -259.14 °C (-434.45 °F)

Molecular Hydrogen benefits

• Anti-inflammatory
  It has anti-inflammatory effects. It helps to decrease swelling in the body.
• Antioxidant
  It is a powerful antioxidant. It helps to balance harmful free radicals in the body that can cause damage to cells and tissues.
• Energy production
  It improves energy production in the body by improving the efficiency of the mitochondria [powerhouses of the cells].
• Brain function
  It has neuroprotective effects. It helps to enhance cognitive function and decrease the risk of neurological diseases.
• Exercise performance
  Molecular hydrogen may help to improve exercise performance by reducing muscle fatigue and increasing endurance.

Hydrogen Ion

“A hydrogen ion is a positively charged ion & created when a hydrogen atom removes its electron. The symbol H⁺ represents it”.

In aqueous solutions, the concentration of hydrogen ions determines the acidity or basicity of the solution. The hydrogen ion in an aqueous solution is considered “wet” or hydrated and is called a hydronium ion:
H₂O + H⁺ → H₃O⁺

The hydronium ion is the solvated proton. Other examples of the solvated proton are NH₄⁺, CH₃, OH₂⁺ & H₃SO₄⁺ ions.

NH₃ + H⁺ → NH₄⁺ (ammonium)
CH₃OH + H⁺→ CH₃OH₂⁺ (methyloxonium)
H₂SO₄ + H⁺→ H₃SO₄⁺

The hydrogen ion is formed when hydrogen compounds are dissolved and solvated. The energy of the solvation process ruptures the bond, and a proton H⁺ is produced. It is liberated from water by reagents with an oxidation potential of 0.414 V or more. Because of the tiny volume of the lone proton, the hydrogen ion has an exceedingly high density of positive charge. Thus, it is permanently attached to an unshared pair of electrons of a solvent molecule or can occupy a lattice site.

Conclusive evidence for H₃O⁺ has been obtained by NMR, IR, and Raman spectra studies of some hydrogen compounds. Acids provide solvated hydrogen ions in water.

Water-exhibits self ionization.
H₂O → H⁺ + CH^–
2H₂O → H₃O⁺ + OH^–

There are other compounds in which weak self-ionization of hydrogen takes place e.g.

2H₂SO₄ → H₃SO₄⁺ + HSO4^–
2NH₃ → NH₄⁺ + NH2^–

The well-known neutralization reaction of classical bases with H₃O⁺ ion is as follows:
H₃O⁺ + OH^– → 2 H₂O

The anions of weak acids act as bases in the presence of hydrogen ions. The weaker the parent acid, the stronger its action with hydrogen ions will be.

CN^– + H⁺ → HCN
NH₂^– + H⁺ → NH₃
CH₃COO^– + H⁺ → CH₃COOH

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Hydrogen Bond

It is a weak chemical bond between hydrogen and an electronegative atom such as oxygen, nitrogen, or fluorine. The hydrogen atom in this bond forms a covalent link with one electronegative atom while also being attracted to another closed electronegative atom, resulting in a partially electrostatic interaction. The electronegativity difference between an electronegative atom and a Hydrogen atom is a type of dipole-dipole interaction.

Electronegativity measures an atom’s ability to attract electrons toward itself in a covalent bond. In the case of hydrogen bonding, the electronegative atom in one molecule or region of a molecule has a partial negative charge because it attracts the shared electrons in the covalent bond with hydrogen more strongly. In contrast, the hydrogen atom has a partial positive charge because it is less electronegative.

The power of a Hydrogen bond is less as compared to a covalent bond. However, it is still strong enough to have an effect on the features and behavior of molecules and materials. The distance, angle & type between electronegative atoms and hydrogen shows how strong a hydrogen bond is.

Many biological processes including the construction of DNA, the folding of proteins and the physical characteristics of liquids like water, depend on hydrogen bonds. In biological systems, hydrogen bonds can also be involved in binding enzymes to substrates and in the recognition of molecules by receptors. It is also essential in the structure and properties of many other materials like polymers.

dipole-dipole forces

These forces are intermolecular forces that occur between polar molecules. These forces occur because of electrostatic attraction between the positive end of one polar molecule and the opposite end having a negative charge of another polar molecule. These forces are relatively weak compared to chemical bonds, but they can still significantly affect the properties and behavior of molecules and materials.

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Isotopes of Hydrogen

There exist 3 Types of Isotopes for which names and details are given below:

• Protium
• Deuterium
• Tritium

Protium

Protium is the most common isotope of hydrogen with one proton and one electron & has no neutron. It is often called “ordinary hydrogen” and makes up about 99.98% of all hydrogen on Earth. Protium has an atomic number of 1 and a standard atomic weight of 1.007825 u. It has no color, odor, or taste & is highly flammable and reactive. In most of the chemical reactions, petrochemicals, fertilizers and semiconductors, Protium is used.

• Reaction with oxygen
  Protium reacts with oxygen to form water.
  2H₂ + O₂ → 2H₂O
• Reaction with chlorine
  Protium reacts with chlorine to form hydrogen chloride.
  H₂ + Cl₂ → 2HCl
• Reaction with metals
  Protium reacts with metals such as sodium and potassium to form metal hydrides.
  2Na + H₂ → 2NaH
• Combustion reaction
  Protium is highly flammable and can burn in the presence of oxygen to form water and release energy.
  2H₂ + O₂ → 2H₂O + energy

Deuterium

Deuterium is an isotope of hydrogen containing one proton, electron, and neutron. It is also called heavy hydrogen because it is twice as heavy as protium. Deuterium has an atomic number of 1 and a standard atomic weight of 2.0141018 u. It is a stable, non-radioactive, naturally occurring element located in trace amounts of water and organic compounds.

Preparation of Deuterium

It can be obtained by the following two methods from water.

1. By fractional distillation.
2. By electrolysis.

An electric current is passed in ordinary water with sodium hydroxide in the latter process. As a result, light hydrogen comes off first, and water containing heavy hydrogen remains. Thus, by decomposing large amounts of water, a small amount of residual water will get richer with combined deuterium as D₂O.

• If heavy water (deuterium oxide) is dropped on sodium, D₂ in gaseous form is obtained
  2 Na + 2D₂O → 2 NaOD + D₂.
• Ortho and para forms of D₂ molecules exist at a temperature in the ratio 2:1, respectively.
• In compounds, deuterium exchanges with ordinary hydrogen in several compounds.
  D₂O + H₂O → 2 HDO

Many Deuterium compounds may be formed. Some of them are given below along with their method of preparation.

Compound	Preparation
D3PO4	3D2O + P2O5 → 2D3PO4
D2SO4	D2O + SO3 → D2SO4
DF	D2 + AgF → 2Ag + 2DF (at 110o C)
ND3 (Heavy Ammonia)	3D2O + Mg3N2→ 2ND3 + 3MgO
CD4 (Deutero Methane)	6D2O + Al4C3 → 3CD4 + 2Al2O3
C2D2 (Deutero Acetylene)	D2O + CaC2→ C2D2 + Cao
HOD	HSD + H2O → HOD + HSH

Tritium

Tritium has one proton, one electron and two neutrons. It is a radioactive and unstable element. It is also known as hydrogen-3 or H-3. Tritium is relatively rare and usually produced artificially in nuclear reactors or particle accelerators. Tritium can pose a health hazard if ingested or inhaled. It can emit beta particles, damaging living tissues and increasing the risk of cancer. Therefore, handling tritium requires special precautions and safety measures.

• Tritium can react with oxygen to form tritiated water, used as a tracer in various biological and environmental studies.
  T₂ + O₂ → 2HTO

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Hydrogen Peroxide (H₂O₂)

Hydrogen Peroxide is a chemical compound that is a pale blue liquid with a slightly sharp odor at room temperature. It is a powerful oxidizing agent.

• Chemical Formula: H₂O₂
• Molecular Weight: 34.01 g/mol
• Density: 1.11 g/mL
• Boiling Point: 150.2 °C (302.4 °F)
• Melting Point: -0.43 °C (31.23 °F)

Hydrogen Peroxide is a highly reactive compound due to the existence of the unstable peroxide bond [-O-O-], which can easily break down to produce water and oxygen. This property makes it a powerful oxidizing and strong bleaching agent, which is why it is used in many industrial and household applications.

Food grade Hydrogen Peroxide

• Food grade hydrogen peroxide also denoted as FGHP, is a high-purity form of hydrogen peroxide used in the food industry for different purposes. It is typically sold in concentrations of 35%, much higher than the hydrogen peroxide found in drugstores, usually 3% or less.
• FGHP is a bleaching agent to whiten flour, starch, and other food products. It is also disinfected to sanitize food preparation surfaces, equipment and utensils. It is used as a preservative to increase the life of particular food products.
• When using FGHP, it is essential to handle it with care as it can be dangerous if not used properly. The concentrated form of FGHP can cause skin irritation, burns, and even blindness if it comes into contact with the eyes. Therefore, wearing protective gloves and goggles is essential when working with FGHP.
• FGHP should never be ingested in its concentrated form, as it can be harmful and even deadly. It should only be utilized as prescribed by a professional in the food industry and kept in a dry, cool and ventilated area away from direct sunlight.

Baking Soda and Hydrogen Peroxide

These are two ordinary home items that can be used together for different purposes. When mixed, they create a chemical reaction that produces oxygen, which can help with cleaning and whitening.

• 2 H₂O₂ + 2 NaHCO₃ → 2 H₂O + 2 CO₂↑ + O₂↑ + 2 NaOH
  The reaction occurs because baking soda is a base, which means it can react with the acidic hydrogen peroxide to form water and carbon dioxide. The oxygen gas is produced as a byproduct of this reaction.
• When they are mixed, they create a chemical reaction that produces oxygen gas.
• This oxygen gas can help lift stains and break down organic matter, making the mixture an effective cleaning agent.
• It is also commonly used as a household cleaner, as the mixture can help remove stains and disinfect surfaces.
• They are generally safe and non-toxic but can be abrasive and potentially damaging to certain surfaces. Always test a small, inconspicuous area before using the mixture on a larger scale. The mixture should be used sparingly and cautiously, as overuse can damage tooth enamel or cause skin irritation.

Hydrogen Peroxide Cleaner

Making hydrogen peroxide is as simple as mixing equal amount of hydrogen peroxide and water in a spray container to create a handy and adaptable cleanser. It can disinfect various surfaces, including kitchen counters, bathroom fixtures and carpets. Testing a small, hidden area first is essential to avoid any potential bleaching or damage to sensitive surfaces.

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