Strontium, a soft, silvery-white metallic element, is a naturally occurring component of the Earth’s crust. It is found primarily within various minerals, such as strontianite and celestine. While it is not found freely in nature, its presence is notable in many geological formations.
The Early Identification of Strontianite
In 1790, Irish physician Adair Crawford, along with his colleague William Cruickshank, began examining this distinct mineral in the lead mines near the village of Strontian, Scotland. They observed that it possessed properties different from other known minerals, particularly barium-containing compounds like witherite, leading them to conclude it contained a new, unknown substance or “earth.”
This newly recognized mineral, later named strontianite (strontium carbonate), was the first indication of strontium’s existence. In 1791, Scottish chemist and physician Thomas Charles Hope further investigated the mineral. Hope confirmed the presence of a unique element within strontianite, noting its characteristic crimson-red flame test color, a property that distinguished it from other elements.
Isolation and Confirmation of the Element
While the mineral strontianite was identified in the 1790s, isolating the pure metallic element proved to be a more significant challenge. This breakthrough was achieved in 1808 by the renowned English chemist Humphry Davy. Davy, a pioneer in the field of electrochemistry, successfully isolated strontium using the then-novel technique of electrolysis.
His method involved passing an electric current through a mixture containing strontium chloride and mercuric oxide, a process that separated the pure metal. This achievement was part of Davy’s broader efforts to isolate several other alkaline earth metals, including calcium and barium, demonstrating the power of electrolysis in chemical discovery. Davy’s work confirmed strontium as a distinct metallic element, moving beyond the identification of its mineral form to its elemental isolation.
The Naming and Chemical Significance
The element received its name, strontium, directly from the village of Strontian in Scotland, where the mineral strontianite was first discovered. This naming convention honored the geographical origin of its initial identification. Humphry Davy himself formalized the name “strontium” to align with the nomenclature of other newly isolated elements.
The discovery and isolation of strontium held considerable chemical significance, contributing to the understanding of elemental classification. As an alkaline earth metal, strontium was placed in Group 2 of the periodic table, alongside elements like calcium and barium, due to its similar chemical properties and reactivity. This discovery helped to expand the knowledge of how elements relate to one another and further solidified the developing principles of chemical periodicity.