decay level
21Isotopes of dubnium — Dubnium (Db) is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 261Db in 1968. There are 12 known radioisotopes from 256Db to …
22Dubnium — rutherfordium ← dubnium → seaborgium Ta ↑ Db ↓ (Upp) …
23Rutherfordium — (pronEng|ˌrʌðɚˈfɔrdiəm) is a chemical element in the periodic table that has the symbol Rf and atomic number 104. This is a radioactive synthetic element whose most stable known isotope is 267Rf with a half life of approximately 1.3 hours.… …
24dating — I In geology and archaeology, the process of determining an object s or event s place within a chronological scheme. Scientists may use either relative dating, in which items are sequenced on the basis of stratigraphic clues (see stratigraphy) or …
25Radioactive waste — 2007 ISO radioactivity danger logo, designed in part for long term radioactive waste depositories which might survive into a far future time in which all knowledge of the meaning of present common radiation danger symbols and signs has been lost… …
26Radon — This article is about the chemical element. For other uses, see Radon (disambiguation). astatine ← radon → francium Xe ↑ Rn ↓ Uuo …
27spectroscopy — spectroscopist /spek tros keuh pist/, n. /spek tros keuh pee, spek treuh skoh pee/, n. the science that deals with the use of the spectroscope and with spectrum analysis. [1865 70; SPECTRO + SCOPY] * * * Branch of analysis devoted to identifying… …
28Atom — The atom is the smallest unit of an element that retains the chemical properties of that element. An atom has an electron cloud consisting of negatively charged electrons surrounding a dense nucleus. The nucleus contains positively charged… …
29Water fluoridation — Fluoridation does not affect the appearance, taste or smell of drinking water.[1] Water fluoridation is the controlled addition of fluoride to a public water supply to reduce tooth decay. Fluoridated water has flu …
30luminescence — luminescent, adj. /looh meuh nes euhns/, n. 1. the emission of light not caused by incandescence and occurring at a temperature below that of incandescent bodies. 2. the light produced by such an emission. [1885 90; < L lumin (see LUMEN) +… …
