| 释义 |
Definition of protactinium in English: protactiniumnoun ˌprəʊtakˈtɪnɪəmˌproʊˌtækˈtiniəm mass nounThe chemical element of atomic number 91, a radioactive metal of the actinide series, occurring in small amounts as a product of the natural decay of uranium. （化学元素）镤（符号： Pa ） Example sentencesExamples - The dates of discovery of these elements as 1789 for uranium, 1829 for thorium, 1899 for actinium and 1913 for protactinium.
- Along the way, these disintegration series produce radioactive isotopes of protactinium, thorium, actinium, radium, francium, radon, astatine, polonium, bismuth, lead, thallium and mercury.
- All isotopes of protactinium are radioactive.
- A new method of radioactive tracing involves the use of a new clock, based on the radioactive decay of uranium - 235 to protactinium - 231.
- A protactinium - 234 atom has 91 protons and 143 neutrons.
OriginEarly 20th century: from proto- 'original, earlier' + actinium, so named because one of its isotopes decays to form actinium. Definition of protactinium in US English: protactiniumnounˌproʊˌtækˈtiniəmˌprōˌtakˈtēnēəm The chemical element of atomic number 91, a radioactive metal of the actinide series, occurring in small amounts as a product of the natural decay of uranium. （化学元素）镤（符号： Pa ） Example sentencesExamples - A new method of radioactive tracing involves the use of a new clock, based on the radioactive decay of uranium - 235 to protactinium - 231.
- The dates of discovery of these elements as 1789 for uranium, 1829 for thorium, 1899 for actinium and 1913 for protactinium.
- All isotopes of protactinium are radioactive.
- A protactinium - 234 atom has 91 protons and 143 neutrons.
- Along the way, these disintegration series produce radioactive isotopes of protactinium, thorium, actinium, radium, francium, radon, astatine, polonium, bismuth, lead, thallium and mercury.
OriginEarly 20th century: from proto- ‘original, earlier’ + actinium, so named because one of its isotopes decays to form actinium. |