Ion

Author: Leandro Alegsa Creation date: November 13, 2022

An ion is an electrically charged atom or group of atoms. It can be made from an atom, or from a group of atoms (molecule). It is "charged" so it will move near electricity. This is because atoms are made of three smaller parts:

neutrons (with no charge),
number of protons with positive charges and
equal number of negatively-charged electrons.

An ion has unequal numbers of protons and electrons. Making an ion from an atom or molecule is called ionization.

The charge on a proton is chosen as +1 (positively charged). The charge on an electron is opposite to the charge on the proton. The charge on the electron is -1 (negatively charged). An atom that is ionized makes two parts, one positive, and one negatively charged. For example, a neutral hydrogen atom has one proton and one electron. Ionizing the atom breaks it into two parts: (1) a positively charged hydrogen ion, H+ (2) a negatively charged electron.

A liquid with ions is called an electrolyte. A gas with lots of ions is called a plasma. When ions move, it is called electricity. For example, in a wire, the metal ions do not move, but the electrons move as electricity. A positive ion and a negative ion will move together. Two ions of the same charge will move apart. When ions move they also make magnetic fields.

Many ions are colourless. Elements in the main groups in the Periodic Table form colourless ions. Some ions are coloured. The transition metals usually form coloured ions.

Term History

The term ion is derived from Ancient Greek ἰόν ión, German 'das Gehende' (present participle active neuter to Ancient Greek ἰέναι iénai, German 'to go').

In his investigations into electricity, Michael Faraday was dissatisfied with the terms available to him for describing chemical decompositions under the influence of electric current. He therefore turned to William Whewell, among others, at the beginning of 1834. The latter suggested the terms ion, cation and anion, among others; they have been used by Faraday ever since. They then spread rapidly in scientific nomenclature.

Formation of ions

Ions form from atoms when they donate or accept electrons. Although the separation of charges requires energy, the ions formed can be energetically favourable if they have particularly stable configurations, for example if they fulfil the octet rule.

Cations

Positively charged ions, so-called cations, are formed when atoms donate electrons. Since the atomic nucleus still has an identical, positive charge (in the neutral atom, the number of protons in the nucleus corresponds exactly to the number of electrons surrounding it), the ion appears in its entirety as a positively charged particle.

Example: metal ions are usually positively charged.
Equation for sodium ion formation: Na → Na+ + e-Equation
for magnesium ion formation: Mg → Mg2+ + 2e-
Equation for aluminum ion formation: Al → Al3+ + 3e-equation for
tin ion formation: Sn → Sn4+ + 4e-.

Anions

Negatively charged ions (anions) are formed by atoms taking up electrons. This results in an excess of electrons (negative charge carriers), which is no longer balanced by the protons (positive charge carriers) present - the negative charges predominate, the ion is negatively charged.

Example: Non-metal ions are usually negatively charged.
Equation for chloride ion formation: Cl + e- → Cl-equation
for sulfide ion formation: S + 2e- → ^S2-

Mobile ions form spontaneously when salts are dissolved in polar solvents (water), e.g.

${\mathrm {{NaCl_{{(s)}}}{\longrightarrow }{Na_{{(aq)}}^{+}}+{Cl_{{(aq)}}^{-}}}}$

The index "s" stands for Latin solidus or English solid, "solid". The index "aq" stands for aquatized.

As an example, the aqueous milieus of cells and organisms (electrolyte solution) can be mentioned. Here they play a decisive role for the electrical processes at membranes, especially for the excitability (membrane potential, action potential).

If common salt and water are mixed, the sodium and chloride ions are dissolved in the water, i.e. separated from each other and individually surrounded by water molecules.

Questions and Answers

Q: What is an ion?

A: An ion is an electrically charged atom or group of atoms. It can be made from an atom, or from a group of atoms (molecule).

Q: How are ions created?

A: Ions are created through a process called ionization, which involves making an unequal number of protons and electrons in the atom or molecule.

Q: What is the charge on a proton?

A: The charge on a proton is +1 (positively charged).

Q: What is the charge on an electron?

A: The charge on an electron is -1 (negatively charged).

Q: What happens when ions move?

A: When ions move, it creates electricity and magnetic fields.

Q: Are all ions colourless?

A: No, some ions are coloured while others are colourless. Elements in the main groups in the Periodic Table form colourless ions, while transition metals usually form coloured ions.