Isotopes: There are 20 known isotopes of strontium, 4 stable and 16 unstable. Natural strontium is a mixture of the 4 stable isotopes. Properties: Strontium is softer than calcium and decomposes more vigorously in water. Finely divided strontium metal ignites spontaneously in air. Strontium is a silvery metal, but it rapidly oxidizes to a yellowish color. Because of its propensity for oxidation and ignition, strontium is typically stored under kerosene. Strontium salts color flames crimson and are used in fireworks and flares. Uses: Strontium-90 is used in Systems for Nuclear Auxilliary Power (SNAP) devices. Strontium is used in producing glass for color television picture tubes.
In contrast, a SKU, or Stock Keeping Unit, is a number assigned to a product by the company for stock-keeping purposes and internal operations. The UPC code is affixed to a product wherever it is sold, remaining a constant throughout the productâs shelf life.
Since a SKU is unique to the company, the same product would have different SKUs if sold by different companies, but they would have the same UPC. Another difference is that SKUs are typically eight alpha-numeric digits, while UPCs are 12 digits, numeric only.