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An ion is an atom or molecule that has lost or acquired one or more of its valence electrons, resulting in a net positive or negative electrical charge. In other terms, a chemical species has an unbalanced number of protons (positively charged particles) and electrons (negatively charged particles). Michael Faraday, an English scientist and physicist, used the word “ion” to characterise the chemical species that moves from one electrode to another in aqueous solution in 1834. The term ion is derived from the Greek word ion, which means “to travel.” Despite the fact that Faraday was unable to identify the particles moving between electrodes, he knew that metals dissolved into a solution at one electrode and another metal was deposited from the solution at the other electrode, implying that matter was moving under the influence of an electrical current.
Ions Can Be Divided Into Several Types:
Cations and anions are the two types of ions respectively.
- a) Cations: Cations are ions with a net positive charge due to the fact that the number of protons in the species outnumbers the number of electrons. A superscript after the formula that denotes the charge number and a “+” symbol indicates the formula for a cation. The plus symbol is preceded by a number if it exists. The charge is +1 if only a “+” is present. Ca2+, for example, is a +2 charge cation.
- b) Anions: Anions are negatively charged ions. The electrons in anions outnumber the protons by a factor of two. An atom’s, functional groups, or molecule’s number of neutrons has no bearing on whether they are anions or not. An ion’s charge is represented by a superscript after the chemical formula, just as cations. The chlorine anion, for example, has a single negative charge and is denoted by the symbol Cl (-1). The negative symbol is preceded by a number in the superscript. The sulphate anion, for instance, is denoted by the symbol SO42-.
The Interaction of Ions and Dipoles:
The electrostatic contact between a fully charged ion and a neutral molecule with a dipole is known as an ion-dipole interaction. Furthermore, it is an intermolecular force observed most frequently in solutions, particularly ionic compounds dissolved in polar liquids. Which component of the molecule attracts and repels depends on the charge of the ion. As a result, a cation attracts a molecule’s partially negative end, whereas an anion attracts a molecule’s partially positive end.
Ion-dipole interaction as an example:
The ions Na+ and H2O (sodium ion) (water molecule)
A cation is represented by the symbol Na+.
H2O has a somewhat positive end: it starts with H atoms and ends with O atoms.
From the O atom, the partially negative end of H2O is formed. The oxygen atom in a water molecule is attracted to sodium, whereas the hydrogen atom is attracted to it.
Interaction of Ion-Induced Dipoles:
When an ion interacts with a nonpolar molecule, it causes an ion-induced dipole force, which is a weak attraction. When a fully charged ion approaches a nonpolar molecule, the electrons respond by forming a dipole, and the molecule polarises.
A cation polarises the molecule by attracting the electron cloud, whereas an anion polarises the molecule by repelling it.
Ion-Induced Dipoles as an example:
NO3– (nitrate ion) and I2 are examples of ion-induced dipole forces (iodine molecule)
An anion is a molecule with the formula NO3–.
The molecule I2 is a nonpolar one. Iodine molecules become polarised in the presence of nitrate ions.
Ion-Ion Interactions in Molecules:
The interactions between ions (ion-ion interactions) are the most simple to comprehend: similar charges repel each other, whereas opposite charges attract. In the gas phase, these Coulombic forces work across large distances.The force is determined by multiplying the product of the charges (Z1,Z2) by the square of the separation distance (d2):
F = – Z1Z2/d2
Two oppositely charged particles floating around in a vacuum will be attracted to one other, and the attraction will become stronger as they move closer, until they finally stay together and take a significant amount of energy to separate them. They combine to produce an ion-pair, a new particle with a positively and negatively charged surface. Because these ion pairs and free ions have strong connections, the clusters tend to develop and finally fall out of the gas phase as a liquid or solid (depending on the temperature).
Ion-Ion interaction as an example:
When a saturated sodium chloride solution has more ions than the solution can sustain, sodium cations begin to attract chloride anions, forming solid salt crystals. Precipitation processes, in which two aqueous solutions are mixed to produce a solid, demonstrate ion-ion interaction.
Conclusion:
The attraction of ions with opposite charges is known as ion-ion interactions. They’re also known as ionic bonds, and they’re the forces that keep ionic compounds together.
Charges that are similar repel each other, whereas charges that are diametrically opposed attract.
