The discovery of radioactivity by Henri Becquerel in 1896 opened a new field of research for chemists. An immediate and obvious question had to do with the materials that produced the radioactivity that Becquerel observed. In July, 1898, Marie Curie...

Forms of an element that have the same number of protons but differ in their atomic weights are called isotopes of that element. The atomic number of an atom is equal to the number of protons found within its nucleus. The atomic weight of an atom...

Isotopes are variants of the same ELEMENT. Every ATOM of a particular element contains the same number of protons, but some have more neutrons (and therefore weigh more; see ATOMIC WEIGHT). Isotopes are very common in nature: most elements of...

Different forms of atoms of the same element. Atoms consist of a nucleus, containing positively-charged particles (protons) and neutral particles (neutrons), surrounded by negatively-charged particles (electrons). Isotopes of an element differ only in...

Isotopes are any of the several different forms of an element each having different atomic mass (mass number). Isotopes of an element have nuclei with the same number of protons (the same atomic number) but different numbers of neutrons. Therefore,...

Overcoming a critical scarcity of radioactive materials for research Martin Brechbiel had promising results indicating that a radioactive isotope called bismuth-212 could destroy cancers in laboratory animals. Yet his work at the National Cancer Institute in Bethesda, Md., stopped short in April...

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The Canadian House of Commons passed emergency legislation late Tuesday night aimed at bypassing Canada's nuclear safety watchdog and putting a swift end to a critical shortage of medical isotopes.The bill will allow Atomic Energy of Canada Ltd. to immediately restart the 50-year-old reactor at...

Thousands of cancer patients in Canada, the United States and other countries have had their medical tests postponed because of a problem with a Canadian nuclear reactor that produces medical isotopes used to diagnose and treat such cases.The isotope shortage is the result of a...