Charged ions or simply ions are any atoms or group of atoms in a molecule with a net electrical charge which can be either positive or negative due to the removal of electrons from or addition of electrons to the valence shell of the orbitals and 7 important charged ions examples, their classifications are discussed in details.
- H+ or H3O+
- Ions belonging to alkali metals and alkaline earth metals like Na+, K+ , Ca2+ , Mg2+ , Cs+
- Cations belonging to transition metal series
- Oxygen in superoxide, peroxide forms
- Lanthanum ions
1. H+ or H3O+ :
One of the most important charged ion examples is a hydronium ion or hydroxonium cations are produced when Arrhenius acid releases protons in aqueous medium or when a proton combines with H2O molecule to give H3O+ ions as H+ ions do not stay alone in aqueous medium. They are highly studied for their various functionality.
They have a very high conductance in solution due to Grotthuss mechanism. The ability of a molecule and to what extent it produces H+ ions provides magnitude of their acidity.
In crystalline compounds the hydroxonium ions H3O+ , H5O2+ , H7O3+ , H9O4+ , H14O62+ have been characterized.
Structure of : H3O+ is a flat pyramid while that of H5O2+ is a kind of linear structure.
However, structures of other hydroxonium cations are quite complicated and O—H-O distances differ considerably.
Grotthuss mechanism : It is a phenomenon by which a proton moves within the solution rapidly through H-bonding between the H+ and H2O. In other words, there is a rapid exchange of proton resulting in higher conduction.
2. Ions belonging to alkali metals and alkaline earth metals like Na+, K+ , Ca2+ , Mg2+ , Cs+ :
These monopositive ions are formed by losing one electron from their outermost s orbitals in case of alkali metals. They do not form dipositive ions as the configuration obtained after losing its valence shell s electron is that of a noble gas configuration.
Alkaline earth metals form dipositive ions by losing two of its valence electrons. They are formed as they have low ionisation energies to attain stability. Also, their high solvation energy tendency make them stabilised thermodynamically.
Na+, K+ ions play important role in biological processes as Na+ / K+ pump ,Mg2+ is required for many enzymatic reactions like Na+-K+-ATPase, it blocks calcium for easy relaxation of muscles after contraction. Ca2+ is used for circulating blood, relaxing nerve cells, regulating heartbeat activity etc , Cs+ is radioactive and highly toxic, they have been used in nuclear chemistry.
3. Cations belonging to transition metal series :
They display a wide range of oxidation states due to the availability of quite a few number of valence electrons in their (n-1)d and ns orbitals which are less shielded by the innermost electrons. These ions have played role as catalysis, electrodes, electroplating, ores.
Cr3+ ions from enormous number and variety of complexes like Reinecke’s salt, this salt with Cr3+ ion was widely used to precipitate primary and secondary amines, for determination of promazine.
Cr2+ is one of the strongest reducing agents in aqueous solution. Ti2+ forms intense yellow-orange color hence they can be identified using colorimetric determination, they are used for synthetic biomolecules delivery. Fe2+ and Fe3+ is used as a redox couple and is responsible for the oxidation of iron forming rust.
4. Carbocations :
One of the most important topics in organic chemistry. They are charged cations with +1 or more than +1 charge residing on carbon atom that is bonded to only three other atoms thereby leaving one of its tetravalency empty. It contains 6 electrons with an empty p orbital thus acquiring sp2 hybridisation with trigonal planar geometry.
Shape and hybridization of +CR3 where R= H or any other atoms : Common example is a Methyl cation with +1 charge.
5. Carbanions :
They are electrophilic in nature and can be formed by reaction with alkali and alkaline earth metals by heterolytic fission. This charged ion is extremely common and important in organic chemistry.
It adopts a trigonal pyramidal structure similar to NH with the lone pair occupying the tetrahedral valency to avoid repulsion between the bond and lone pairs of electrons.
Shape and hybridization of –CR3 where R= H or any other atoms : Common example is a methyl anion with -1 charge.
6. Oxygen in superoxide, peroxide forms :
Superoxide,O2– , is an oxygen free radical responsible for many biological irregular functions. This radical anion is responsible for the slow tampering with living beings. These reactive oxygen species also play a role of action in antimalarial medicines mechanism.
It is paramagnetic and is weakly attracted to magnetic field. Peroxide,O2– , is diamagnetic as it contains paired electrons.
Bond order of superoxide ion is 1.5 with smaller bond length and forms more stable peroxide compounds with more electropositive elements, and that of peroxide’s bond order is 1 with a greater bond length.
They have wide applications in medicinal chemistry. They are used as Hydrogen peroxide. Peroxides, however, decomposes under sunlight and they have to be kept in dark areas.
7. Lanthanum ions :
They mostly form tripositive cations because of their Zeff value and closely spaced energy levels. They are stable hard lewis acids and reducing agents. They form wide range of complexes that are used as homogenous catalysts for industrial applications. E.g. La3+ , Ln3+ , Eu 3+ .
They are used in batteries, optoelectronics devices, superconductors, rocket fuel, nuclear energy study, transistors etc.
Classification of Charged ions :
- Anionic charged species/anions – These charged ions carry an overall negative charge magnitude. They are formed due to the addition of extra electrons in the valence shells which outdone the protons present in the nucleus of the system/species. Generally, Non-metals show the tendency to gain electrons, mostly down the group and across the right side of the period. Common examples : Cl– , Br– , O2– , SO42- etc.
- Cationic charged species/cations – They carry an overall positive charge due to loss of electrons from their valence shells but the protons number remain the same in the nucleus. Alkali metals, alkaline earth metals, early transition elements show this tendency. Common examples : Na+ , Ca2+ , Mg2+ , Hg+ , Hg2+ , Zn2+ , NH4+ , H3O+ etc.
Note : It can be either a polyatomic ion or a monoatomic ion. The magnitude of the charge can greater or lesser than zero but never equal to zero as the whole definition of charged ions lies in the positive or negative magnitude of charge.
7 most important charged ion examples have been discussed which are broadly classified as H+ or H3O+ ions, alkali metals and alkaline earth metals ions like Na+, K+ , Ca2+, transition metal series ions , Carbocations, Carbanions, superoxide, peroxide, Lanthanum ions.