A hydrogen ion is created when a
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
atom loses or gains an
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no kn ...
. A positively charged hydrogen ion (or
proton
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...
) can readily combine with other particles and therefore is only seen isolated when it is in a gaseous state or a nearly particle-free space. Due to its extremely high charge density of approximately 2×10
10 times that of a sodium ion, the bare hydrogen ion cannot exist freely in solution as it readily hydrates, i.e., bonds quickly. The hydrogen ion is recommended by
IUPAC
The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
as a general term for all
ion
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...
s of
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
and its
isotope
Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...
s.
Depending on the
charge
Charge or charged may refer to:
Arts, entertainment, and media Films
* '' Charge, Zero Emissions/Maximum Speed'', a 2011 documentary
Music
* ''Charge'' (David Ford album)
* ''Charge'' (Machel Montano album)
* ''Charge!!'', an album by The Aqu ...
of the ion, two different classes can be distinguished: positively charged ions and negatively charged ions.
Cation (positively charged)
A hydrogen atom is made up of a nucleus with charge +1, and a single electron. Therefore, the only positively charged ion possible has charge +1. It is noted H
+.
Depending on the isotope in question, the hydrogen cation has different names:
*
Hydron Hydron has the following meanings:
* Hydron (chemistry)
In chemistry, the hydron, informally called proton, is the cationic form of atomic hydrogen, represented with the symbol . The general term "hydron", endorsed by the IUPAC, encompasses cati ...
: general name referring to the positive ion of any hydrogen isotope (H
+)
*
Proton
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...
:
1H
+ (i.e. the cation of
protium)
*
Deuteron
Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two stable isotopes of hydrogen (the other being protium, or hydrogen-1). The nucleus of a deuterium atom, called a deuteron, contains one proton and one n ...
:
2H
+, D
+
*
Triton
Triton commonly refers to:
* Triton (mythology), a Greek god
* Triton (moon), a satellite of Neptune
Triton may also refer to:
Biology
* Triton cockatoo, a parrot
* Triton (gastropod), a group of sea snails
* ''Triton'', a synonym of ''Triturus' ...
:
3H
+, T
+
In addition, the ions produced by the reaction of these cations with water as well as their
hydrates
In chemistry, a hydrate is a substance that contains water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the ...
are called hydrogen ions:
*
Hydronium
In chemistry, hydronium (hydroxonium in traditional British English) is the common name for the aqueous cation , the type of oxonium ion produced by protonation of water. It is often viewed as the positive ion present when an Arrhenius acid is d ...
ion: H
3O
+
*
Zundel cation
In chemistry, hydronium (hydroxonium in traditional British English) is the common name for the aqueous cation , the type of oxonium ion produced by protonation of water. It is often viewed as the positive ion present when an Arrhenius acid is di ...
: H
5O
2+ (named for
Georg Zundel
Georg Zundel (May 17, 1931 – March 11, 2007) was a German physical chemist, tenured professor of biophysics at University of Munich, peace activist, environmentalist and philanthropist.
His father Georg was a painter and his mother was th ...
)
*
Eigen cation
In chemistry, hydronium (hydroxonium in traditional British English) is the common name for the aqueous cation , the type of oxonium ion produced by protonation of water. It is often viewed as the positive ion present when an Arrhenius acid is di ...
: H
9O
4+ (or HO •3HO) (named for
Manfred Eigen
Manfred Eigen (; 9 May 1927 – 6 February 2019) was a German Biophysical chemistry, biophysical chemist who won the 1967 Nobel Prize in Chemistry for work on measuring fast chemical reactions.
Eigen's research helped solve major problems in ...
)
Zundel cations and Eigen cations play an important role in proton diffusion according to the
Grotthuss mechanism.
In connection with acids, "hydrogen ions" typically refers to hydrons.
In the image at left the hydrogen atom (center) contains a single proton and a single electron. Removal of the electron gives a cation (left), whereas addition of an electron gives an anion (right). The hydrogen anion, with its loosely held two-electron cloud, has a larger radius than the neutral atom, which in turn is much larger than the bare proton of the cation. Hydrogen forms the only cation that has no electrons, but even cations that (unlike hydrogen) still retain one or more electrons are still smaller than the neutral atoms or molecules from which they are derived.
Anion (negatively charged)
Hydrogen
anion
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
s are formed when additional electrons are acquired:
*
Hydride
In chemistry, a hydride is formally the anion of hydrogen( H−). The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of ...
: general name referring to the negative ion of any hydrogen isotope (H
−)
* Protide:
1H
−
* Deuteride:
2H
−, D
−
* Tritide:
3H
−, T
−
Uses
Hydrogen ions drive
ATP synthase
ATP synthase is a protein that catalyzes the formation of the energy storage molecule adenosine triphosphate (ATP) using adenosine diphosphate (ADP) and inorganic phosphate (Pi). It is classified under ligases as it changes ADP by the formation ...
in
photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
. This happens when hydrogen ions get pushed across the membrane creating a high concentration inside the
thylakoid membrane
Thylakoids are membrane-bound compartments inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thyl ...
and a low concentration in the cytoplasm. However, because of osmosis, the H
+ will force itself out of the membrane through ATP synthase. Using their
kinetic energy
In physics, the kinetic energy of an object is the energy that it possesses due to its motion.
It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its accele ...
to escape, the protons will spin the ATP synthase which in turn will create
ATP. This happens in
cellular respiration
Cellular respiration is the process by which biological fuels are oxidised in the presence of an inorganic electron acceptor such as oxygen to produce large amounts of energy, to drive the bulk production of ATP. Cellular respiration may be des ...
as well though the concentrated membrane will instead be the inner membrane of the
mitochondria
A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...
.
Hydrogen ions concentration, measured as pH, is also responsible for the
acidic
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
or
basic
BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...
nature of a compound. Water molecules split to form H
+ and hydroxide anions. This process is referred to as the
self-ionization of water
The self-ionization of water (also autoionization of water, and autodissociation of water) is an ionization reaction in pure water or in an aqueous solution, in which a water molecule, H2O, deprotonates (loses the nucleus of one of its hydrogen ...
.
Ocean acidification
The concentration of hydrogen ions and pH are inversely proportional; in an aqueous solution, an increased concentration of hydrogen ions yields a low pH, and subsequently, an acidic product. By definition, an acid is an ion or molecule that can donate a proton, and when introduced to a solution it will react with water molecules (H
2O) to form a hydronium ion (H
3O
+), a conjugate acid of water. For simplistic reasoning, the hydrogen ion (H
+) is often used to abbreviate the hydronium ion.
Ocean acidification
Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...
is the direct consequence of elevated concentrations of hydrogen ions and carbonate saturation from significant absorption of carbon dioxide (CO
2) by the world's oceans. The pre-industrial state of the ocean's carbonate chemistry has been notably stable, including the balance of its pH. Following the industrial revolution, anthropogenic emissions of burning fossil fuels, cement production, and changes in land use, have increased the oceans uptake of carbon dioxide from the atmosphere by 30%. In the ocean, the
absorption capacity of this greenhouse gas is 59 times higher than in the atmosphere; the ocean acts as the largest
carbon sink
A carbon sink is anything, natural or otherwise, that accumulates and stores some carbon-containing chemical compound for an indefinite period and thereby removes carbon dioxide () from the atmosphere.
Globally, the two most important carbon si ...
on the planet, playing a significant role in climate regulation. In addition to carbon fluxes, the natural process of carbon sequestration from the atmosphere into the deep ocean is facilitated by two systems, the biological pump and the solubility pump. The solubility pump is a physico-chemical process that transfers CO
2 at the air-sea interface. Based on Henry's Law, the amount of dissolved CO
2 in an aqueous solution is directly proportional to the partial pressure of CO
2 in the atmosphere. To maintain equilibrium, a state of high atmospheric partial pressure of CO
2 leads to an increased oceanic exchange of this gas by molecular diffusion.
In the surface waters, dissolved atmospheric carbon dioxide (CO
2(aq)) reacts with water molecules to form carbonic acid (H
2CO
3), a weak diprotic acid. Diprotic acids consist of two ionizable hydrogen atoms in each molecule. In an aqueous solution, partial dissociation of carbonic acid releases a hydrogen proton (H
+) and a bicarbonate ion (HCO
3−), and subsequently, the bicarbonate ion dissociates into an additional hydrogen proton and a carbonate ion (CO
32-). The dissolving and dissociating of these inorganic carbon species generate an increase in the concentration of hydrogen ions and inversely lowers ambient surface ocean pH. The carbonate buffering system governs the acidity of seawater by maintaining dissolved inorganic carbon species in chemical equilibrium.
The chemical equation consists of reactants and products that may react in either direction. More reactants added to a system yield more product production (the chemical reaction shifts to the right) and if more product is added, additional reactants will form, shifting the chemical reaction to the left. Therefore, in this model, a high concentration of the beginning reactant, carbon dioxide, produces an increased amount of end-product (H
+ and CO
32-), thus lowering pH and creating a more acidic solution. The natural buffering system of the ocean resist the change in pH by producing more bicarbonate ions generated by free acid protons reacting with carbonate ions to form an alkaline character. However, increasing atmospheric CO
2 concentrations may exceed the buffering capacity threshold, consequently resulting in higher rates of ocean acidification. Shifts in the ocean's carbonate chemistry has the potential to manipulate
ocean biogeochemical cycle
Marine biogeochemical cycles are biogeochemical cycles that occur within Marine habitat, marine environments, that is, in the saline water, saltwater of seas or oceans or the brackish water of coastal Estuary, estuaries. These biogeochemical cy ...
s for many elements and compounds causing profound impacts on marine ecosystems. Furthermore, the solubility of CO
2 is temperature dependent; elevated surface water temperatures reduce CO
2 solubility. A continual rise in atmospheric partial pressure of CO
2 could potentially convert the ocean from acting as sink (the vertical transport of carbon to the depths of the ocean) to becoming a source (CO
2 degassing from the ocean), further increasing global temperatures.
[Matsumoto, K. (2007). Biology-mediated temperature control on atmosphericpCO2and ocean biogeochemistry. Geophysical Research Letters, 34(20). doi:10.1029/2007gl031301]
See also
*
Acid
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
*
Protonation
In chemistry, protonation (or hydronation) is the adding of a proton (or hydron, or hydrogen cation), (H+) to an atom, molecule, or ion, forming a conjugate acid. (The complementary process, when a proton is removed from a Brønsted–Lowry acid, ...
*
Dihydrogen cation
The dihydrogen cation or hydrogen molecular ion is a cation (positive ion) with formula . It consists of two hydrogen nuclei ( protons) sharing a single electron. It is the simplest molecular ion.
The ion can be formed from the ionization of a ...
*
Trihydrogen cation
The trihydrogen cation or protonated molecular hydrogen is a cation (positive ion) with formula , consisting of three hydrogen nuclei ( protons) sharing two electrons.
The trihydrogen cation is one of the most abundant ions in the universe. It ...
References
{{Set index article
Ocean Acidification
Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...