Indium Chemical Properties (25 Facts You Should Know)

Indium is a metallic post-transition element that is 0.21ppm in the crust of the Earth. Let us discuss the Indium facts in detail.

Indium is a byproduct of the zinc refining process and is a small component in zinc sulphide ores. The metal has a melting point lower than that of lithium or tin but higher than that of gallium and sodium. It is a very supple, malleable, and combustible metal.

Let us discuss in brief the chemical properties of indium, such as its atomic number, electronic configuration, allotropic forms, and oxidation states.

Indium symbol

Chemical elements are represented by symbols that provide a brief description. Let us write the chemical symbol for indium.

The letter “In” stands for the chemical symbol for the element indium. The Latin word “indicium,” which signifies indigo or violet, is the source of this name.

indium chemical properties
 Symbol of Indium

Indium group in periodic table

According to the periodic table, a group is an atomic column. Let us check the group for the Indium.

Periodic table group 13 includes indium(In). In Greek terminology, triels mean tri that used for indium, and gallium.

Indium period in periodic table

The elements’ chemical behaviour as their atomic number grows is depicted by the periodic table, which is arranged in rows. Let us predict the Indium period.

Indium (In) can lie in the 5th period of the periodic table. Period 5 elements fill their 5s shells, their 4d, and their 5p shells in that order.

Indium block in periodic table

The block’s atoms share the same physical and chemical characteristics. Let us talk about the indium block.

Indium belongs to the “p-block” because its valence electrons or last electrons are situated in the p-block. It is a component of the post-transition element or metals.

Indium atomic number

The atomic number of an element is a representation of its chemical structure. Let us talk about indium’s atomic number.

The atomic number of indium is 49. It indicates that the element has 49 protons and 49 electrons. 

Indium atomic Weight

The term “atomic weight” refers to an atom’s overall weight. Let us talk about indium’s atomic weight.

The atomic mass of iridium is 114.818 g/mol. Due to this, most of its properties fall between its neighbours, gallium, and thallium.

Indium Electronegativity according to Pauling

The chemical attribute of electronegativity, denoted by the symbol, refers to an atom’s propensity to draw electrons to it. Let us look at the electronegativity value for indium.

Indium has a Pauling electronegativity of 1.78. The atomic number, the separation between the charged nucleus and valence electrons, and a unitless value all have an impact on an atom’s electronegativity.

Indium atomic Density

The ratio of atomic mass to atomic volume is used to calculate atomic density. Let us determine indium atomic density.

Indium has a density of 7.31 g/cm3, which is higher than gallium but lower than thallium. At m.p. of 156.6°C, indium has a liquid-state density of 7.02 g/cm3.

Indium melting point

The temperature at which a particular crystalline lattice melts or transforms into a liquid state is known as the melting point. Let us find out the indium’s melting point.

Indium has a melting point of 429.7485 K, or 156.5985 °C or 313.8773 °F. The melting point of indium is as much low as it melts at 30°C or 86°F. Due to its low temperature, the metal will melt if hold in one hand.

Indium boiling point

The vapour pressure and standard atmospheric pressure at sea level are equal at the boiling point, which is the temperature. Let us determine the indium’s boiling point

Indium has a boiling point of 2345 K (2072 °C, 3762 °F). It has a lower boiling point than gallium but higher than thallium.

Indium Vanderwaals radius

A Vander Waals radius is the distance between two identical atoms that are held together by the attraction of their nuclei. Let us examine the Vander Waals radius of the indium.

Indium has a 193 pm(1pm=1*10‑12 m) van der Waals radius.

Indium ionic/covalent radius

The covalent radius is the distance between two atoms joined by a covalent bond, whereas the ion radius is the ionic radius. Let us discuss the radius of Indium.

Indium has an ionic radius of.80Å (In+3) and a covalent radius of 144 pm (1 = 100 pm) (1.44Å ). Indium has extensive coordination centres and ionic radii as shown in the table below:

Ion(Inn+ )
Ionic Radius
(1pm=1*10‑12 m)
The ionic radius of Indium

Indium isotopes

Chemical elements known as isotopes have identical nuclear charges or atomic numbers in their nuclei. Let us discuss in detail the indium isotopes.

Indium has 39 isotopes, each of which has 97–135 nucleons. There is just one stable isotope of indium found in nature. There are 113-In and other naturally occurring stable indium isotopes. Here only stable isotopes of indium are discussed below in the table:

IsotopeMassHalf-lifeMode of
109In108.907154.2 hβ+109Cd
110In109.907171.15 hβ+110Cd
111In110.905112.8049 dEC111Cd
112In111.9055314.4 mβ+ (56%)
β (44%)
114In114.9049181.198 mβ+ (0.5%)
β (99.5%) 
114m1In190.2949.51 dIT (96.75%)
β+ (3.25%)
115In116.9038794.4 x 1014 yβ115Sn
Isotopes of indium

Indium electronic shell

The electrons’ home is the electronic shell, which can be thought of as a distinct energy state. Let us figure out how many electronic shells there are in indium.

Indium’s electron structure consists of 5 electronic shells. Its respective electronic shells contain 2, 8, 18, 18, and 3 electrons, respectively.

Indium electron configurations

The arrangement of electrons in various electronic shells is known as electron configuration. Let us discuss In’s electron configuration.

The indium electron configurations are as follows: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p1 or [Kr] 4d10 5s2 5p1. The period five elements’ shells are filled 5s, 4d, and 5p in that order.

Indium energy of first ionisation

As part of the ionization process, the first ionisation energy is necessary to liberate a loosely bound electron from a neutral atom. Let us explain for indium.

The first ionisation energy of indium is 558.3 kJ/mol. The first electrons of indium must be removed as follow: In + IE → In+ + e ( [Kr] 4d10 5s2; In→In1+).

Indium energy of second ionisation

The energy required to eject the 2nd electron from an atom’s valence shell is known as the 2nd ionisation energy. Let us determine indium’s second ionisation energy.

The second ionisation energy of indium is 1820.7 kJ/mol. The second ionisation of an electron is substantially higher than the first because it takes more energy to remove it from a full-filled s orbital such as In+ + IE → In2+ + e( [Kr] 4d10 5s1; In1+→In2+).

Indium energy of third ionisation

A dipositive ion requires one electron to be removed from its valence shell with the third ionisation energy. Let us calculate this for indium.

The third ionisation energy of indium is 2704 kJ/mol. Using this energy, the third electron must be taken out of the outermost shell as follows: In2+ + IE → In3+ + e( [Kr] 4d10; In2+→In3+). Due to In2+, the 3rd ionisation energy is relatively high.

Indium oxidation states

The oxidation state or oxidation number of an element refers to how many electrons it receives or loses over time. Let us check out indium’s oxidation state.

Indium is more commonly found in the oxidation state +3. It has Variable oxidation states that include -5,- 2, -1, +1, +2, and +3.

Nature of 
Indium’s oxidation state with a compound

Indium CAS number

A specific number that identifies a chemical element is the CAS registry number. Let us find out the indium’s CAS number.

The CAS registry number of indium is 7440-74-6.

Indium ChemSpider ID

A free database of chemical structures called ChemSpider ID provides a variety of information about the chemical element’s structure. Let us find out for indium.

Indium’s ChemSpider ID is 4514408. 

Indium allotropic forms

The physical characteristics of allotropes are different from those of their chemical equivalents. Let us talk about indium’s allotropic state.

Indium does not exist in an allotropic form. Indium is frequently found in zinc ores and is mostly produced from byproducts of mining zinc ores.

Indium chemical classification 

According to their characteristics and electron configuration, chemical classification systems make an effort to categorise the chemical elements. Let us check for indium.

Here is some chemical classification of indium is discussed below:

  1. Indium dissolves in concentrated alkalies and acids to form indates and indium salts.
  2. Every anhydrous +3 charged indium derivative is covalent, except indium trifluoride (InF3).
  3. The molar heat capacity of indium is 26.74 J/(mol.K).
  4. Indium is so soft that can be cut easily and Mohs hardness is 1.2. 

Indium state at room temperature

Any chemical component’s state is determined by its melting and boiling temperatures, and force of attraction. Let us examine In’s condition at room temperature.

A solid at room temperature is indium. A body-centred tetragonal crystal structure describes indium in its solid state.

Is Indium paramagnetic?

A type of magnetism known as paramagnetism occurs when the magnetic field only faintly attracts the components. Let us determine whether indium has a paramagnetic property or not.

Indium exhibits diamagnetic characteristics due to paired electrons. The indium shows diamagnetism because of its molar magnetic susceptibility, which is -64.0×10−6 cm3/mol at 298 K.


Indium is pure metal that, like tin, emits a high-pitched “cry” when bent. Bright silvery-white lustre metal describes indium. It possesses 47 meta-states, the most stable of which is indium-114m1, which is more stable than its ground state and has a half-life of 49.51 days.