Barium
ALKALINE EARTH METAL
Bohr Model: Electrons arranged in energy shells around the nucleus.
Barium is a chemical element with symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Because of its high chemical reactivity barium is never found in nature as a free element.
Quick Facts
Atomic Number 56
Period 6
Group 2
Phase Solid
Appearance Unknown
About Alkaline Earth Metals
Alkaline earth metals (Group 2) are reactive metals, though less so than alkali metals. They typically lose two electrons to form cations with a +2 charge.
History
Discovered By Carl Wilhelm Scheele
Named By Unknown
Physical Properties
Atomic Mass 137.3277
Density 3.51 g/L
Molar Heat 28.07 J/(mol·K)
Phase Transition (Melting & Boiling Points)
Barium melts at 1000 K and boils at 2118 K.
Atomic Properties
Electron Config [Xe] 6s2
Electronegativity 0.89
Electron Affinity 13.954 kJ/mol
Ionization Energy 502.9 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.