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Francium is a chemical element; it has symbol Fr and atomic number 87. It is extremely radioactive; its most stable isotope, francium-223 (originally called actinium K after the natural decay chain in which it appears), has a half-life of only 22 minutes.
A chemical element is a chemical substance whose atoms all have the same number of protons.The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8, meaning each oxygen atom has 8 protons in its nucleus.
The abundance of the chemical elements is a measure of the occurrences of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by mass fraction (in commercial contexts often called weight fraction), by mole fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases), or by volume fraction.
Loss of potency requires periodic replacement of the source in radiotherapy and is one reason why cobalt machines have been largely replaced by linear accelerators in modern radiation therapy. [175] Cobalt-57 (Co-57 or 57 Co) is a cobalt radioisotope most often used in medical tests, as a radiolabel for vitamin B 12 uptake, and for the ...
The first light bulbs ever lit by electricity generated by nuclear power at EBR-1 at Argonne National Laboratory-West, December 20, 1951. [7]The process of nuclear fission was discovered in 1938 after over four decades of work on the science of radioactivity and the elaboration of new nuclear physics that described the components of atoms.
San Francisco, [23] officially the City and County of San Francisco, is a commercial, financial, and cultural center within Northern California.With a population of 808,988 residents as of 2023, [14] San Francisco is the fourth-most populous city in the U.S. state of California and the 17th most populous in the U.S.
Connecticut (/ k ə ˈ n ɛ t ɪ k ə t / ⓘ kə-NET-ih-kət) [10] is a state in the New England region of the Northeastern United States.It borders Rhode Island to the east, Massachusetts to the north, New York to the west, and Long Island Sound to the south.
The soybean, soy bean, or soya bean (Glycine max) [3] is a species of legume native to East Asia, widely grown for its edible bean, which has numerous uses.. Traditional unfermented food uses of soybeans include soy milk, from which tofu and tofu skin are made.