Dec 6, 2025 · The rate at which a radioactive element decays is expressed in terms of its half-life; i.e., the time required for one-half of any given quantity of the isotope to decay.

A radioactive isotope, also known as a radioisotope, radionuclide, or radioactive nuclide, is any of several species of the same chemical element with different masses whose nuclei are unstable and …

Dec 6, 2025 · Radium is a radioactive chemical element that is the heaviest of the alkaline-earth metals of the periodic table. Radium is a silvery white metal that does not occur free in nature.

Dec 13, 2025 · It is now known that uranium, radioactive in all its isotopes, consists naturally of a mixture of uranium-238 (99.27 percent, 4,510,000,000-year half-life), uranium-235 (0.72 percent, …

Dec 5, 2025 · Plutonium (Pu), radioactive chemical element of the actinoid series of the periodic table, atomic number 94. It is the most important transuranium element because of its use as fuel in certain …

Physical science - Radioactivity, Transmutation, Elements: The discovery of radioactivity by the French physicist Henri Becquerel in 1896 is generally taken to mark the beginning of 20th-century physics.

In 1898 French physicists Pierre and Marie Curie discovered the strongly radioactive elements polonium and radium, which occur naturally in uranium minerals. Marie coined the term radioactivity for the …

Technetium, chemical element, synthetic radioactive metal of Group 7 (VIIb) of the periodic table, the first element to be artificially produced.

Dec 3, 2025 · The rate at which a radioactive element decays is expressed in terms of its half-life; i.e., the time required for one-half of any given quantity of the isotope to decay.

Dec 6, 2025 · As radioisotopes are identical chemically with stable isotopes of the same element, they can take the place of the latter in physiological processes. Moreover, because of their radioactivity, …