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Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal , calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium .
Like the periodic table, the list below organizes the elements by the number of protons in their atoms; it can also be organized by other properties, such as atomic weight, density, and electronegativity. For more detailed information about the origins of element names, see List of chemical element name etymologies.
Mendeleev arranges the 63 elements known at that time (omitting terbium, as chemists were unsure of its existence, and helium, as it was not found on Earth) into the first modern periodic table and correctly predicts several others. 31 Gallium: 1875 P. E. L. de Boisbaudran: 1878 P. E. L. de Boisbaudran and E. Jungfleisch
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 ...
The history of the periodic table is also a history of the discovery of the chemical elements. The first person in recorded history to discover a new element was Hennig Brand, a bankrupt German merchant. Brand tried to discover the philosopher's stone—a mythical object that was supposed to turn inexpensive base metals into gold.
The periodic table, also known as the periodic table of the elements, is an ordered arrangement of the chemical elements into rows ("periods") and columns ("groups"). It is an icon of chemistry and is widely used in physics and other sciences.
Once an element has been named, a one- or two-letter symbol must be ascribed to it so it can be easily referred to in such contexts as the periodic table. The first letter is always capitalized. While the symbol is often a contraction of the element's name, it may sometimes not match the element's English name; for example, "Pb" for lead (from ...
The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). [1] The elements have very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure. [2]