noun Chemistry, Physics.
- former name of meitnerium. Symbol: Une
noun Chemistry, Physics.
- a superheavy, synthetic, radioactive element. Symbol: Mt; atomic number: 109.
noun Chemistry, Physics.
- meitnerium.
noun
- a synthetic element produced in small quantities by high-energy ion bombardment. Symbol: Mt; atomic no: 109
Mt
- A synthetic, radioactive element that is produced by bombarding bismuth with iron ions. Its most long-lived isotopes have mass numbers of 266 and 268 with half-lives of 3.4 milliseconds and 70 milliseconds, respectively. Atomic number 109. See Periodic Table.