Hydron (chemistry)

Hydron (chemistry)

In chemistry, a hydron is the general name for a cationic form of atomic hydrogen, represented with the symbol H+
. The term "proton" refers to the cation of protium, the most common isotope of hydrogen. The term "hydron" includes cations of hydrogen regardless of their isotopic composition: thus it refers collectively to protons (1H+) for the protium isotope, deuterons (2H+ or D+) for the deuterium isotope, and tritons (3H+ or T+) for the tritium isotope. Unlike other ions, the hydron consists only of a bare atomic nucleus.

The hydron (a completely free or "naked" hydrogen atomic nucleus) is too reactive to occur in many liquids, even though it is sometimes visualized to do so by students of chemistry. A free hydron would react with a molecule of the liquid to form a more complicated cation. Examples are the hydronium ion in water-based acids, and H
, the unstable cation of fluoroantimonic acid, the strongest superacid. For this reason, in such liquids including liquid acids, hydrons diffuse by contact from one complex cation to another, via the Grotthuss mechanism.[1]

The hydrated form of the hydrogen cation, the hydronium (hydroxonium) ion H
(aq), is a key object of Arrhenius' definition of acid. Other hydrated forms, the Zundel cation H
which is formed from a proton and two water molecules, and the Eigen cation H
, a hydronium ion and three water molecules, play an important role in "hydron hopping" according to the Grotthuss mechanism. The hydron itself is crucial in more general Brønsted–Lowry acid–base theory, which extends the concept of acid–base chemistry beyond aqueous solutions.

The negatively charged counterpart of the hydron is the hydride anion, H


  • Isotopes of hydron 1
  • History of the term 2
  • See also 3
  • References 4

Isotopes of hydron

  1. Proton, having the symbol p or 1H+, is the +1 ion of protium, 1H.
  2. Deuteron, having the symbol 2H+ or D+, is the +1 ion of deuterium, 2H or D.
  3. Triton, having the symbol 3H+ or T+, is the +1 ion of tritium, 3H or T.

Other isotopes of hydrogen are too unstable to be relevant in chemistry.

History of the term

The term "hydron" is recommended by IUPAC to be used instead of "proton" if no distinction is made between the isotopes proton, deuteron and triton, all found in naturally occurring undifferentiated isotope mixtures. The name "proton" refers to isotopically pure 1H+.[2] On the other hand, referring to the hydron as simply hydrogen ion is not recommended because hydrogen anions also exist.[3]

The term "hydron" was defined by IUPAC in 1988.[4][5] Traditionally, the term "proton" was and is used in place of "hydron".require('Module:No globals')

local p = {}

-- articles in which traditional Chinese preceeds simplified Chinese local t1st = { ["228 Incident"] = true, ["Chinese calendar"] = true, ["Lippo Centre, Hong Kong"] = true, ["Republic of China"] = true, ["Republic of China at the 1924 Summer Olympics"] = true, ["Taiwan"] = true, ["Taiwan (island)"] = true, ["Taiwan Province"] = true, ["Wei Boyang"] = true, }

-- the labels for each part local labels = { ["c"] = "Chinese", ["s"] = "simplified Chinese", ["t"] = "traditional Chinese", ["p"] = "pinyin", ["tp"] = "Tongyong Pinyin", ["w"] = "Wade–Giles", ["j"] = "Jyutping", ["cy"] = "Cantonese Yale", ["poj"] = "Pe̍h-ōe-jī", ["zhu"] = "Zhuyin Fuhao", ["l"] = "literally", }

-- article titles for wikilinks for each part local wlinks = { ["c"] = "Chinese language", ["s"] = "simplified Chinese characters", ["t"] = "traditional Chinese characters", ["p"] = "pinyin", ["tp"] = "Tongyong Pinyin", ["w"] = "Wade–Giles", ["j"] = "Jyutping", ["cy"] = "Yale romanization of Cantonese", ["poj"] = "Pe̍h-ōe-jī", ["zhu"] = "Bopomofo", }

-- for those parts which are to be treated as languages their ISO code local ISOlang = { ["c"] = "zh", ["t"] = "zh-Hant", ["s"] = "zh-Hans", ["p"] = "zh-Latn-pinyin", ["tp"] = "zh-Latn", ["w"] = "zh-Latn-wadegile", ["j"] = "yue-jyutping", ["cy"] = "yue", ["poj"] = "hak", ["zhu"] = "zh-Bopo", }

local italic = { ["p"] = true, ["tp"] = true, ["w"] = true, ["j"] = true, ["cy"] = true, ["poj"] = true, } -- Categories for different kinds of Chinese text local cats = { ["c"] = "", ["s"] = "", ["t"] = "", }

function p.Zh(frame) -- load arguments module to simplify handling of args local getArgs = require('Module:Arguments').getArgs local args = getArgs(frame) return p._Zh(args) end function p._Zh(args) local uselinks = not (args["links"] == "no") -- whether to add links local uselabels = not (args["labels"] == "no") -- whether to have labels local capfirst = args["scase"] ~= nil

        local t1 = false -- whether traditional Chinese characters go first
        local j1 = false -- whether Cantonese Romanisations go first
        local testChar
        if (args["first"]) then
                 for testChar in mw.ustring.gmatch(args["first"], "%a+") do
          if (testChar == "t") then
           t1 = true
          if (testChar == "j") then
           j1 = true
        if (t1 == false) then
         local title = mw.title.getCurrentTitle()
         t1 = t1st[title.text] == true

-- based on setting/preference specify order local orderlist = {"c", "s", "t", "p", "tp", "w", "j", "cy", "poj", "zhu", "l"} if (t1) then orderlist[2] = "t" orderlist[3] = "s" end if (j1) then orderlist[4] = "j" orderlist[5] = "cy" orderlist[6] = "p" orderlist[7] = "tp" orderlist[8] = "w" end -- rename rules. Rules to change parameters and labels based on other parameters if args["hp"] then -- hp an alias for p ([hanyu] pinyin) args["p"] = args["hp"] end if args["tp"] then -- if also Tongyu pinyin use full name for Hanyu pinyin labels["p"] = "Hanyu Pinyin" end if (args["s"] and args["s"] == args["t"]) then -- Treat simplified + traditional as Chinese if they're the same args["c"] = args["s"] args["s"] = nil args["t"] = nil elseif (not (args["s"] and args["t"])) then -- use short label if only one of simplified and traditional labels["s"] = labels["c"] labels["t"] = labels["c"] end local body = "" -- the output string local params -- for creating HTML spans local label -- the label, i.e. the bit preceeding the supplied text local val -- the supplied text -- go through all possible fields in loop, adding them to the output for i, part in ipairs(orderlist) do if (args[part]) then -- build label label = "" if (uselabels) then label = labels[part] if (capfirst) then label = mw.language.getContentLanguage():ucfirst( The latter term is generally only used in the context where comparisons between the various isotopes of hydrogen is important (as in the kinetic isotope effect or hydrogen isotopic labeling). Otherwise, referring to hydrons as protons is still considered acceptable, for example in such terms as protonation, deprotonation, proton pump or proton channel. The transfer of H+
in an acid-base reaction is usually referred to as proton transfer. Acid and bases are referred to as proton donors and acceptors correspondingly.

However, although 99.9844% of natural hydrogen nuclei are protons, the remainder (about 156 per million in sea water) are deuterons (see deuterium). A rare triton also occurs (see tritium).

See also


  1. ^ [1] Computer modeling of proton-hopping in superacids.
  2. ^ Nomenclature of Inorganic Chemistry-IUPAC Recommendations 2005 Red Book 2005.pdf IR-3.3.2, p.48
  3. ^ Compendium of Chemical Terminology, 2nd edition McNaught, A.D. and Wilkinson, A. Blackwell Science, 1997 [ISBN 0-86542-684-8], also online
  4. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version:  (2006–) "hydron".
  5. ^