Electrovalency

Electrovalency

Electrovalency is a measurement of the net electric charge of an ion and is used when balancing chemical reactions. Electrovalency is related to the concepts of electronegativity and valence electrons, and indicates the number of electrons necessary for an ion to have a balanced electric charge.

Atoms that have an almost full or almost empty valence shells tend to be very reactive. Atoms that are strongly electronegative (as is the case with halogens) often only have one or two missing electrons in their valence shell, and frequently bond with other molecules or gain electrons to form anions. Atoms that are weakly electronegative (such as alkali metals) have relatively few valence electrons that can easily be lost to atoms that are strongly electronegative. As a result, weakly electronegative atoms tend to lose their electrons and form cations.

The electrovalency of an element or compound is expressed as a charge. Atoms or molecules that have lost electrons have an electrovalency greater than zero and are known as cations. When an atom or molecule gains electrons, it is called an anion. When an atom or molecule has an electrovalency of zero, it has no net electric charge. When writing about an ion, the convention is to write the chemical formula followed by the electrovalency as a superscript, illustrated below:

Ag+, Co2+, Fe3+, CN, CO32−, PO43−.

When an ion only contains a single atom it is called a monatomic ion, and when it contains more than one atom, it is called a polyatomic ion. On the above list, Ag+ would be a monatomic cation and PO43− would be a polyatomic anion.

Electrovalency tables

These tables show the charges of ions formed by common elements and compounds. These tables are used to determine the proportion of a particular element in a compound, and also to predict the products of a reaction.

"For information on naming conventions, see the chemical nomenclature pages for organic and inorganic compounds"

Table of common anions


Charge

−1 −2 −3
Dihydrogen phosphate (H2PO4) Monohydrogen phosphate (HPO42−) Phosphate (PO43−)
Hydrogen carbonate (HCO3) Carbonate (CO32−) Nitride (N3−)
Hydrogen sulfate (HSO4) Sulfate (SO42−)
Hydrogen sulfite (HSO3) Sulfite (SO32−)
Hydrogen sulfide (HS) Sulfide (S2-)
Aluminate (Al(OH)4) Zincate (Zn(OH)42−)
Superoxide (O2) Oxide (O2−)
Hydride (H) Peroxide (O22−)
Fluoride (F) Thiosulfhate (S2O32−)
Chloride (Cl) Chromate (CrO42−)
Bromide (Br) Dichromate (Cr2O72−)
Iodide (I) Silicate (SiO32−)
Hydroxide (OH)
Acetate (ethanoate) (CH3COO)
Hypochlorite (ClO)
Chlorate (ClO3)
Nitrate (NO3)
Nitrite (NO2)
Cyanide (CN)
Permanganate (MnO4)

Table of common cations


Charge

+1 +2 +3 +4
Copper I (Cu+) Copper II (Cu2+) Aluminium (Al3+) Tin IV (Sn4+)
Silver (Ag+) Iron II (Fe2+) Iron III (Fe3+) Lead IV (Pb4+)
Hydrogen (H+) Beryllium (Be2+) Chromium III (Cr3+)
Lithium (Li+) Magnesium (Mg2+)
Sodium (Na+) Calcium (Ca2+)
Potassium (K+) Strontium (Sr2+)
Ammonium (NH4+) Barium (Ba2+)
Hydronium (H3O+) Manganese II (Mn2+)
Zinc (Zn2+)
Mercury I (Hg22+)
Mercury II (Hg2+)
Tin II (Sn2+)
Lead II (Pb2+)

Electrovalency in chemical reactions

Electrovalency is used to help balance equations describing chemical reactions. In the following equation, hydronium and hydroxide combine to form water:

H3O+ + OH → 2H2O0

One can see that the one positively charged hydronium molecule and one negatively charged hydroxide molecule have formed water which has an electrovalency of zero.

See also

*Octet rule
*Radical (chemistry)


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Look at other dictionaries:

  • electrovalency — elektroninis valentingumas statusas T sritis fizika atitikmenys: angl. electrovalency vok. Elektrovalenz, f rus. электровалентность, f pranc. électrovalence, f; valence électrochimique, f …   Fizikos terminų žodynas

  • electrovalency — e·lec·tro·va·len·cy (ĭ lĕk trō vāʹlən sē) n. Electrovalence. * * * …   Universalium

  • electrovalency — noun a) The net electric charge on an ion b) The number of electrons gained or lost during the formation of an ionic bond See Also: electrovalent …   Wiktionary

  • electrovalency — /əlɛktroʊˈveɪlənsi/ (say uhlektroh vayluhnsee), /i / (say ee ) noun the valency of an ion, equal to the number of electrons lost or gained by the atom which becomes the ion. Also, US, electrovalence. –electrovalent, adjective …   Australian-English dictionary

  • electrovalency — noun see electrovalence * * * electrovaˈlency or electrovaˈlence noun Union within a chemical compound achieved by transfer of electrons, the resulting ions being held together by electrostatic attraction (cf ↑covalency) • • • Main Entry:… …   Useful english dictionary

  • electrovalence — “+ noun or electrovalency “+ Etymology: electr + valence, valency : valence characterized by the transfer of one or more electrons from one atom to another with the formation of ions (as in sodium chloride and other simple salts); also : the… …   Useful english dictionary

  • Electron counting — is a formalism used for classifying compounds and for explaining or predicting electronic structure and bonding. Many rules in chemistry rely on electron counting:*Octet rule for main group elements, especially the lighter ones such as carbon,… …   Wikipedia

  • electrovalence — electrovalent, adj. electrovalently, adv. /i lek troh vay leuhns/, n. Chem. 1. Also called polar valence. the valence of an ion, equal to the number of positive or negative charges acquired by an atom through a loss or gain of electrons. 2. Also… …   Universalium

  • electrovalent — adjective Of or pertaining to electrovalency / electrovalence …   Wiktionary

  • electrovalent — [ɪˌlɛktrə(ʊ) veɪl(ə)nt] adjective Chemistry (of bonding) ionic. Derivatives electrovalence noun electrovalency noun Origin 1920s: from electro + valent, on the pattern of trivalent …   English new terms dictionary

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