Indium is a post-transition metal that makes up 0.21 parts per million of the Earth’s crust. Very soft and malleable, indium has a melting point higher than sodium and gallium, but lower than lithium and tin. Chemically, indium is similar to gallium and thallium.
Protons and Neutrons in Indium
Indium is a chemical element with atomic number 49 which means there are 49 protons in its nucleus. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19 coulombs.
The total number of neutrons in the nucleus of an atom is called the neutron number of the atom and is given the symbol N. Neutron number plus atomic number equals atomic mass number: N+Z=A. The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z.
For stable elements, there is usually a variety of stable isotopes. Isotopes are nuclides that have the same atomic number and are therefore the same element, but differ in the number of neutrons. Mass numbers of typical isotopes of Indium are 113.
Main Isotopes of Indium
Indium occurs in 2 natural isotopes: 113In and 115In. 115In is very slightly radioactive, decaying by beta decay with a half-life of 4.41×1014 years and at the same time it is the most common isotope, having a natural abundance more than 95%.
Indium-113 is composed of 49 protons, 64 neutrons, and 49 electrons.
Indium-115 is composed of 49 protons, 66 neutrons, and 49 electrons.
Electrons and Electron Configuration
The number of electrons in an electrically-neutral atom is the same as the number of protons in the nucleus. Therefore, the number of electrons in neutral atom of Indium is 49. Each electron is influenced by the electric fields produced by the positive nuclear charge and the other (Z – 1) negative electrons in the atom.
Since the number of electrons and their arrangement are responsible for the chemical behavior of atoms, the atomic number identifies the various chemical elements. The configuration of these electrons follows from the principles of quantum mechanics. The number of electrons in each element’s electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. In the periodic table, the elements are listed in order of increasing atomic number Z.
Electron configuration of Indium is [Kr] 4d10 5s2 5p1.
Possible oxidation states are +3.
Most Common Application of Indium
The primary consumption of indium worldwide is for LCD production. Indium tin oxide is one of the most widely used transparent conducting oxides because of its electrical conductivity and optical transparency, as well as the ease with which it can be deposited as a thin film. ITO is a mixed oxide of indium and tin with a melting point in the range 1526–1926 °C, depending on composition.
|Number of protons||49|
|Number of neutrons (typical isotopes)||113|
|Number of electrons||49|
|Electron configuration||[Kr] 4d10 5s2 5p1|
Properties of other elements