Ionization Definition:

Ionization is defined as the process through which electrically neutral atoms are converted to electrically charged atoms (ions).
Or you can say the process by which ions are formed is known as ionization.

You must be familiar with the concept of ions, an ion is simply an atom with an electrical charge. It is categorized into two broad categories; positive ions and negative ions or cations and anions. A positive ion is formed when an atom loses an electron. Conversely, a negative ion is formed when an atom gains an electron. We have already explained the concept of ions, its types, and everything related to ions, comprehensively.

Ionization Uses:

The fluorescent lamp and other electrical discharge lamps are present examples of gas ionization. Geiger-muller counter and ionization chambers illustrate the uses of ionization as radiation detectors. The basic equipment of fundamental science has a wide scope of ionization usage such as mass spectrometry and in the industry as radiation therapy.

Ionization Formula

X + energy → X+ + e−
Here X is an atom or molecule that will go through the ionization process. X+ is that atom from which an electron will be removed, and the removed electron is denoted by e−.

What is the Ionization Process?

The process of Ionization involves the loss or gain of an electron from any given atom or molecule. If an atom or molecule gains an electron, it becomes negatively charged (an anion), and if it loses an electron, it becomes positively charged (a cation). Sometimes when an ion comes into formation, the energy is lost or gained.

Ionization Equation

As we have already discussed a general formula of ionization, we will now explain ionization with an example and tell you how to write an ionization equation. Dilute solution of vinegar also known as acetic acid (HC2H3O2). Carbonated water is a solution of carbonic acid (H2CO3). We will now write an ionization equation of each acid when placed into water.

Note: both of these acids are weak acids. When multiple hydrogen ions are involved in the process of ionization, weak acid ionizes one hydrogen ion at a time. Including balancing of the equation and the current state of matter.


The acidic hydrogen atoms are at the beginning of the formulas. The other hydrogen atoms are not acidic.

The water removes acidic hydrogen (H+) from the acid and becomes a hydronium ion (H3O+).

The acid that has lost the H+ (the conjugate base) then gets a negative charge.

We write the equation as an equilibrium because both the forward and reverse processes are occurring at the same time.

Acetic Acid


Carbonic Acid

Carbonic acid ionizes in two steps.



What is Ionization Energy

The specific amount of energy needed to emit one electron from the outermost shell of a neutral atom is called Ionization energy.

Or you can also say that the minimum amount of energy required to remove the loosely bound electron from an atom of a molecule. Source: Wikipedia

Different elements have different ionization energy, represented by “First Ionization Energy” or ‘I’, “Second Ionization Energy” or ‘I2′ and so on.

This is an endothermic process. This means that the close the outermost electron is to the nucleus, the higher will be ionization energy of that particular atom.

This ionization energy is measured differently in Physics and Chemistry. In Physics, this ionization energy is measured by the amount of energy required to remove a single electron from the valence shell known as an electron volt.

In Chemistry, it is measured by the amount of energy required for all atoms to lose one electron known as enthalpy and is represented by kilojoules per mole

Ionization of Water

Water is an amphiprotic molecule, it can act as a very weak acid and a very weak base, donating protons to itself to a limited extent:
2H2O (l)⇌H3O+(aq)+OH−(aq)

Individual molecules do not remain ionized for a long time, the reaction is rapid towards both sides of the equilibrium. The equation above illustrates the Grotthuss mechanism of how hydrogen bonding makes the protons tunnel from one water molecule to the next. Auto-ionization of water occurs similarly with separation of ions H+ and OH–, which recombine in a matter of femtoseconds. The lifetime of the separated ions is about 70 microseconds and depends on the extent of hydrogen bonding, so it is shorter at lower temperatures.

Equilibrium Constant

The electrical conductivity of pure water is 0.055 µS/cm. Svante Arrhenius said this must be due to the presence of ions by water ionization reaction
2H2O (l)⇌H3O+(aq)+OH−(aq)

Any aqueous solution and pure form of water have this equilibrium.

What is Ionization Potential?

Ionization potential is also referred to as the ionization energy or ionization enthalpy, the specific amount of power or energy that must be given to a gaseous atom/molecule to emit the outermost electron from it. Mostly it is denoted by a symbol ‘Ei’ and its system international unit is kilojoules per mole (kJ/mol).

Atoms consist of a positively charged nucleus that is surrounded by electrons that are placed in definite orbitals. Since the electrons are negatively charged, they are attracted to the nucleus via electrostatic forces. To remove an electron from an atom, an input of energy is required to overcome the electrostatic force acting on the electron. The amount of energy required here is known as the ionization potential of the atom in the discussion.

Factors that determine the Ionization Potential of any given Atom

The magnitude of Nuclear Charge

All the positively charged protons in an atom are concentrated in the nucleus. Hence, the elements possessing a higher atomic number will certainly have a higher number of protons in their present nuclei and having a greater nuclear charge. The greater the magnitude of the positive charge held by the nucleus, the stronger the force of attraction between the nucleus and the electrons and the greater the ionization potential of the atom.

Atomic Radii

The force of attraction between the nucleus and the valence electrons depends on two factors:

  • Effective Nuclear Charge
  • Distance Between the Nucleus and the Valence Electron

As the distance between the nucleus and the valence electrons increases (due to the addition of new electron shells), the force of attraction between the nucleus and the outermost shell decreases. Therefore, the task of isolating an electron from its valence shell in a smaller atomic radius is difficult as compared to an atom with a greater atomic radius.

Shielding Offered by Inner-shell Electrons

The electrons in the valence shell of an atom are subject to repulsive forces from the inner shell electrons (electron-electron repulsions). In a way, the inner shells are shielding the valence electrons by nuclear attractive forces.

Therefore, the magnitude of nuclear charge and the extent of inner-shell shielding are dependent on the nuclear attractive forces present between the outermost electrons and the nucleus itself. The greater the shielding effect, the lower the ionization energy of that atom.

The strong nuclear charge affecting an electron, denoted by Zeff, depends upon the ext of shielding forces and the magnitude of nuclear charge to denote the net positive charge acting on the electron in question. Needless to say, the lower the value of Zeff, the lower the ionization potential of the atom.

Occupancy of the Atomic Orbital

Atoms with highly stable electron configuration have a lower tendency to lose electrons. For example, half-empty or filled atomic orbitals determine the stability of an atom. The added stability makes it difficult to remove electrons from the atom.

Hence, The ionization enthalpy of the atom is affected by the tenancy of the atomic orbitals and the stability of the electron configuration.

nth Ionization Potential

The removal of multiple electrons from an atom is a step-by-step process in which a single electron is removed in each step. The energy required to remove an electron from a cation holding a positive charge of magnitude +1 is called the second ionization potential and can be expressed via the following reaction.
X+ + IE2 → X2+ + e–

Where IE2 is the second ionization potential of the atom in the discussion. familiar equations could be written for the third and fourth ionization potential of an atom.

X2+ + IE3 → X3+ + e–
X3+ + IE4 → X4+ + e–

The (n-1)the potential of an atom is almost always smaller in magnitude than the nth potential. The reason being that the nuclear charge acting upon the electron increase as the magnitude of the positive charge held by the ion increases. The nth ionization energy of an atom can be defined as the amount of energy required to remove an electron from the atom when it holds a charge of (n-1).

What is the Ionization of Air?

What is the Process of the Ionization of Air
Through Air ionization, the static charge on insulated and isolated objects is neutralized by creating an equilibrium source of positively and negatively charged ions. Whatever static charge is present on objects in the work environment will be reduced and neutralized by attracting opposite polarity charges from the air. Because it uses only the air that is already present in the work environment, air ionization may be employed even in cleanrooms where chemical sprays and some static dissipative materials are not usable.

Necessary non-conductors (i.e. process-required insulators) in the environment cannot lose their electrostatic charge by attachment to the ground. Ionization neutralizes the charge on these non-conductive items (circuit board materials and examples of necessary non-conductive items include some device packages). Assessment of the ESD hazard created by electrostatic charges on the necessary non-conductors in the workplace is required to ensure that appropriate actions are implemented, commensurate with the risk to ESDS items.

How Do Air Ionizers Create Ions?

There are two methods of air ionizers working. The first is alpha ionization, which uses a nuclear source such as polonium 210. The polonium 210 particles collide with the air, transferring electrons, causing the neutral air molecules to become negative ions. Since the polonium loses electrons, it becomes a positive ion. Alpha ionizers are beneficial because they create an equal number of positive and negative ions.

The use of electrical current to create bipolar ionized air is known as corona Ionization. The ionizer applies a high-voltage electrical current composed of a flow of negatively charged electrons, to a metal prong or needle. Electrostatic repulsion causes the electrons to detach from the prong or needle, attaching themselves to the molecules of nitrogen and oxygen in the air, forming negative ions, which are attracted to the static charge in the work environment thus neutralizing it. These ions also attract certain types of molecules in the work environment like dust and other air particulates. These particulates cluster around the ion, weighing it down and forcing it to fall to the ground, cleaning the air.

Uses of Air Ionizers:

To remove any impure particles from the air, Air ionizers are used in air purifiers. They use electrostatic attraction to attract charged ions from the airborne particles. Any deliberate plate within the air cleaner or any grounded conductor or simply the nearest wall or ceiling then attract these particles and they get diffused.

Ionization Radiation

Ionization radiation means radiation having enough energy that during an interaction with an atom, it tends to remove tightly bound electrons from the orbit of an atom, causing the atom to become charged or ionized.

Here one type of radiation is under question, ionizing radiation, they are of two forms – waves or particles.

Forms of electromagnetic radiation. These differ only in frequency and wavelength.

  • Heatwaves
  • Radiowaves
  • Infrared Light
  • Visible Light
  • Ultraviolet Light
  • X RaysGamma Rays

The longer wavelength, lower frequency waves (heat and radio) have less energy than the shorter wavelength, higher frequency waves (X and gamma rays). Not all electromagnetic (EM) radiation is ionizing. Only the high-frequency portion of the electromagnetic spectrum of X rays and gamma rays are ionizing.

Effects of Ionized Radiations on Health:

Radiation can cause severe damage to tissues and organs depending upon the amount of radiation our body has been exposed to or absorbed which is expressed in a unit called the Gray (Gy). The damage also depends upon the type of radiation our body has been exposed to as well as the parts of the body that have been exposed because each tissue or organ has different levels of sensitivity and tolerance.

Types of Exposures to Ionized Radiation:

There are two different types of exposures of ionizing radiation which are as follows.

Internal Exposure:

This type of exposure occurs when some ionized material has been inhaled, ingested, or has entered into your bloodstream through wounds or infected injections. The only way to treat this exposure is either by eliminating that radionuclide from the body or by excreta or by proper hospitalized treatment.

External Exposure:

External exposure is less dangerous as compared to internal exposure. Its causes include radioactive dust, liquid or aerosols coming in contact with your skin or clothes. By washing your skin or getting rid of infected clothes can simply undo this exposure.

Ionization Vs Dissociation

Ionization and dissociation are two related terms that express almost the same meaning but are used at different occasions. Ionization may refer to different types of separations. It can be ionization of atoms by the removal of electrons or the formation of ions in a liquid solution. Dissociation, on the other hand, is the separation of a substance into smaller constituents such as atoms, ions, or radicals. The main difference between ionization and dissociation is that ionization always forms electrically charged particles whereas dissociation may or may not form electrically charged particles.

Frequently Asked Questions

What Does Ionization Mean?

Ionization means the loss or gain of an electron from any given atom or molecule. If an atom or molecule gains an electron, it becomes negatively charged (an anion), and if it loses an electron, it becomes positively charged (a cation).

What is Ionization Power?

The ionization power means the ionizing of ionizing radiation i.e, how many ions are formed in a given area when the radiation passes through it. Alpha particles have a double charge and are very massive compared to beta particles. So we can conclude that alpha particles have higher ionization power than beta particles.

What Causes Ionization?

Ionization can be caused through the decay of radiations by the internal conversion process, in which an active nucleus gives its energy to any of its inner-shell electrons causing it to be removed.

What Is Ionization Energy?

The ionization energy is the energy required to remove an electron from its orbital around an atom to a point where it is no longer associated with that atom. The ionization energy of any given element increases as you move across a period in the periodic table.

What is Ionization Enthalpy?

Ionization Enthalpy of elements is the amount of energy that an isolated gaseous atom requires to lose an electron in its ground state. Losing of electrons results in the formation of cations.

What is an Example of Ionization?

When sodium and chlorine are combined together to make a salt, the sodium atom gives up an electron that forms a positive charge while chlorine takes that electron and becomes negatively charged.

Are Ionization Energy and Ionization Potential the Same?

Ionization energy and ionization potential are basically synonyms, the amount of energy required, or the amount of potential required to remove an electron from an isolated atom or molecule. There is ionization energy for each successive electron removed; the ionization energy associated with the removal of the first (most loosely held) electron, however, ionization energy is most commonly used.

What is Meant by Ionization Potential?

The ionization potential of ionization enthalpy or ionization energy is the amount of energy that must be given to a gaseous atom/molecule to eject a valence electron from it. Denoted by the symbol ‘Ei’ and SI unit is kilojoules per mole (kJ/mol).

Size of the Positive Nuclear Charge

As the nuclear charge on an atom increases the attraction force between electron increases. Thus the ionization increases.

Size of Atom (Distance of Valence Electron From the Atomic Nucleus)

As Atomic Size Increases, the Attraction of the Positive Nucleus for the Negative Electrons D Less Energy is Required to Remove an Electron. This Means That the Ionization Energy Decreases.

Screening (Shielding) Effect of Inner Shell Electrons

When the shielding increases, the forces of attraction of the positive nucleus for the negative electron decreases, and less energy is needed to remove any valence electrons. This means that the ionization energy decreases.

Why Does Ionization Take Energy?

For any given atom, the electrons present in the outermost shells require less ionization energy as compared to inner shell electrons. As more electrons are added to a nucleus, the outer electrons become shielded from the nucleus by the inner shell electrons. Therefore energy is necessary for the ionization process to take place.

What is Ionization? Detailed Guide On Definition, Equation, Examples, Types, Formation & Energy
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What is Ionization? Detailed Guide On Definition, Equation, Examples, Types, Formation & Energy
What is ionization and how it is performed? To learn more about ions definition, formation, types, examples, and equations read this detailed guide in 2021.
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