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Police code. A police code is a brevity code, usually numerical or alphanumerical, used to transmit information between law enforcement over police radio systems in the United States. Examples of police codes include "10 codes" (such as 10-4 for "okay" or "acknowledged"—sometimes written X4 or X-4), signals, incident codes, response codes, or ...
List of chemical elements. 118 chemical elements have been identified and named officially by IUPAC. A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z ). [1]
The periodic table is a graphic description of the periodic law, which states that the properties and atomic structures of the chemical elements are a periodic function of their atomic number. Elements are placed in the periodic table according to their electron configurations , [41] the periodic recurrences of which explain the trends in ...
e. This list of chemical elements named after places includes elements named both directly and indirectly for places. 41 of the 118 chemical elements have names associated with, or specifically named for, places around the world or among astronomical objects. 32 of these have names tied to the Earth and the other 10 have names connected to ...
Throughout the history of chemistry, many chemical elements have been discovered. In the 19th century, Dmitri Mendeleev formulated the periodic table, a table of elements which describes their structure. Because elements have been discovered at various times and places, from antiquity through the present day, their names have derived from ...
Main article: List of chemical elements naming controversies. The naming of the synthetic elements dubnium and seaborgium generated a significant amount of controversy, referred to as the Transfermium Wars. The Americans wished to name element 105 hahnium, while the Russians preferred the name dubnium. The Americans also wished to name element ...
Chemical symbol. The periodic table, elements being denoted by their symbols. Chemical symbols are the abbreviations used in chemistry, mainly for chemical elements; but also for functional groups, chemical compounds, and other entities. Element symbols for chemical elements, also known as atomic symbols, normally consist of one or two letters ...
Theodor Benfey's arrangement is an example of a continuous (spiral) table. First published in 1964, it explicitly showed the location of lanthanides and actinides.The elements form a two-dimensional spiral, starting from hydrogen, and folding their way around two peninsulas, the transition metals, and lanthanides and actinides.