Francium (Fr). Diagram of the nuclear composition,electron configuration,chemical data,and valence (outer electron) orbitals of an atom of francium-223 (atomic number: 87),the most stable isotope of this element. The nucleus consists of 87 protons (red) and 136 neutrons (orange). 87 electrons (white) successively occupy available electron shells (rings). Francium is a radioactive alkali metal in group 1,period 7,and the s-block of the periodic table. Named after France,it was discovered in 1939 by Marguerite Perey. Francium-223 forms in uranium and thorium ores. It has a half-life of 22 minutes,emitting a beta or alpha particle from its unstable nucleus | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Clarivan, Carlos |
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