Indium
POST-TRANSITION METAL
Bohr Model: Electrons arranged in energy shells around the nucleus.
Indium is a chemical element with symbol In and atomic number 49. It is a post-transition metallic element that is rare in Earth's crust. The metal is very soft, malleable and easily fusible, with a melting point higher than sodium, but lower than lithium or tin.
Quick Facts
Atomic Number 49
Period 5
Group 13
Phase Solid
Appearance silvery lustrous gray
About Post-Transition Metals
Transition metals are elements with partially filled d-orbitals. They are hard, have high melting points, and often form colored compounds.
History
Discovered By Ferdinand Reich
Named By Unknown
Physical Properties
Atomic Mass 114.8181
Density 7.31 g/L
Molar Heat 26.74 J/(mol·K)
Phase Transition (Melting & Boiling Points)
Indium melts at 429.7485 K and boils at 2345 K.
Atomic Properties
Electron Config [Kr] 4d10 5s2 5p1
Electronegativity 1.78
Electron Affinity 37.043 kJ/mol
Ionization Energy 558.3 kJ/mol
Orbital Filling Diagram
This diagram visualizes electron configuration according to the Aufbau principle and Hund's rule.
Boxes represent orbitals (s, p, d, f), while arrows indicate electrons with spin up or down.
Electrons fill lower energy levels first and occupy orbitals singly before pairing.
Photograph
External Resources
Study Guide
Atomic Number
The number of protons in the nucleus, which defines the element.
Atomic Mass
The average mass of an atom, including protons and neutrons.
Electronegativity
A measure of how strongly an atom attracts electrons in a bond.
Ionization Energy
The energy required to remove an electron from an atom.
Electron Config
The arrangement of electrons in the atom's energy shells.