Sb121

Sb-121 is a stable isotope of the element antimony (Sb) with a mass number of 121. It contains 51 protons and 70 neutrons. As a stable nuclide, Sb-121 does not decay and has an effectively infinite half-life.

In natural antimony, there are two stable isotopes: 121Sb and 123Sb. The 121Sb isotope accounts for about 57.36% of natural antimony, while 123Sb accounts for about 42.64%. The weighted average atomic mass of natural antimony is approximately 121.76 u, reflecting the contributions of these two isotopes.

Sb-121 is encountered in isotopic analyses, metallurgical studies, and geochemistry as part of the element’s natural isotopic signature. Isotope-ratio measurements involving 121Sb and 123Sb are performed with mass spectrometry and are used for process tracing, calibration, and studying material provenance. Because isotopes of the same element have nearly identical chemical properties, Sb-121 behaves chemically like Sb-123 in common antimony compounds such as antimony oxide and antimony sulfide.

Notes: Sb-121 and Sb-123 are the two stable isotopes of antimony that together make up the naturally occurring element. The distinction between them is primarily of interest in precise isotopic measurements and research on material sources and geochemical processes. See also antimony and Sb-123.