Chromium
TRANSITION METAL
Bohr Model: Electrons arranged in energy shells around the nucleus.
Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point.
Quick Facts
Atomic Number 24
Period 4
Group 6
Phase Solid
Appearance silvery metallic
About 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 Louis Nicolas Vauquelin
Named By Unknown
Physical Properties
Atomic Mass 51.99616
Density 7.19 g/L
Molar Heat 23.35 J/(mol·K)
Phase Transition (Melting & Boiling Points)
Chromium melts at 2180 K and boils at 2944 K.
Atomic Properties
Electron Config [Ar] 3d5 4s1
Electronegativity 1.66
Electron Affinity 65.21 kJ/mol
Ionization Energy 652.9 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.