Strontium
ALKALINE EARTH METAL
Bohr Model: Electrons arranged in energy shells around the nucleus.
Strontium is a chemical element with symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when it is exposed to air.
Quick Facts
Atomic Number 38
Period 5
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 William Cruickshank (chemist)
Named By Unknown
Physical Properties
Atomic Mass 87.621
Density 2.64 g/L
Molar Heat 26.4 J/(mol·K)
Phase Transition (Melting & Boiling Points)
Strontium melts at 1050 K and boils at 1650 K.
Atomic Properties
Electron Config [Kr] 5s2
Electronegativity 0.95
Electron Affinity 5.023 kJ/mol
Ionization Energy 549.5 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.