What Is Strontium?
Carrying the symbol Sr and atomic number 38, Strontium is classified as an alkaline earth metal, one row down from the alkali metals.
A soft silver metal that burns red. Used in fireworks and signal flares.
As a alkaline earth metal in Period 5 and Group 2 (Alkaline Earth Metals), strontium's placement on the table reflects its electron configuration of [Kr] 5s², which governs its bonding behavior and the type of compounds it typically forms.
Position on the Periodic Table
Strontium is located in Period 5, which continues the transition metal pattern seen in Period 4 but one principal shell further out.
Within that row, strontium sits in Group 2 (Alkaline Earth Metals), alongside elements that share a similar number of valence electrons and, by extension, similar chemical behavior.
This position is not arbitrary — the periodic table was deliberately organized so that an element's row and column reveal its expected reactivity, bonding pattern, and physical state at a glance.
Physical & Chemical Properties
Strontium has an atomic mass of 87.620 u and a density of 2.64 g/cm³. Its melting point is 777°C and its boiling point is 1382°C.
Strontium readily loses its two outer electrons to form a stable +2 ion, a pattern consistent across the whole alkaline earth group.
Electron Configuration Explained
Strontium's electron configuration is [Kr] 5s², describing how its electrons are distributed across shells and subshells around the nucleus.
Reading the configuration in order shows electrons filling shells of increasing energy, following the standard Aufbau principle that explains how atomic structure builds up across the periodic table.
The outermost (valence) electrons shown in this configuration are what ultimately determine strontium's chemical reactivity and the type of bonds it forms with other elements.
History & Discovery
Strontium was formally discovered in 1790, A. Crawford, identified through the careful isolation and analytical techniques typical of that era's chemical research.
Many elements from this period were anticipated by Dmitri Mendeleev's periodic table, which successfully predicted gaps corresponding to undiscovered elements well before laboratory instruments existed to confirm them directly.
What Is Strontium Used For?
Strontium's specific properties make it useful in several applications, including:
- Fireworks (red color)
- Signal flares
- CRT screens
- Bone cancer treatment
- Ceramic magnets
These uses reflect strontium's underlying classification as a alkaline earth metal, since the same properties that define its category in chemistry also determine where it becomes practically useful.
Fun Facts About Strontium
- Strontium gives fireworks and flares their brilliant red color.
- Strontium is element number 38 on the periodic table, in Period 5 and Group 2.
- Its standard atomic mass is 87.620 u, calculated from the natural abundance of its isotopes.
Frequently Asked Questions
What is Strontium's atomic number?
Strontium has atomic number 38.
What is Strontium's chemical symbol?
Strontium's symbol is Sr.
What group and period is Strontium in?
Strontium is in Period 5, Group 2 (Alkaline Earth Metals).
What is Strontium's atomic mass?
Strontium's standard atomic mass is 87.620 u.