91Cr

91Cr is a radioactive isotope of chromium. Chromium typically has 24 protons. The mass number 91 indicates that this isotope has 91 nucleons in its nucleus, meaning it has 24 protons and 67 neutrons. 91Cr is an unstable isotope, meaning it decays over time to form more stable elements. Its primary decay mode is beta-minus decay, where a neutron in the nucleus transforms into a proton and an electron (beta particle), and an antineutrino. This process results in the formation of a molybdenum isotope. The half-life of 91Cr is approximately 15.3 seconds. This means that after 15.3 seconds, half of a sample of 91Cr will have decayed. Due to its short half-life and radioactive nature, 91Cr is not found in significant quantities naturally on Earth. It is typically produced in laboratories or as a byproduct of nuclear reactions, such as in nuclear reactors or particle accelerators. Its short half-life makes it unsuitable for most practical applications, but it can be used in certain research contexts involving nuclear physics or radiochemistry.