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Natural calcium is a mixture of five stable isotopes (40 Ca, 42 Ca, 43 Ca, 44 Ca, and 46 Ca) and one isotope with a half-life so long that it is for all practical purposes stable (48 Ca, with a half-life of about 4.3 × 10 19 years). Calcium is the first (lightest) element to have six naturally occurring isotopes.
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 definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
Calcium oxide (formula: Ca O), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic , alkaline , crystalline solid at room temperature . The broadly used term lime connotes calcium-containing inorganic compounds , in which carbonates , oxides , and hydroxides of calcium, silicon , magnesium ...
The most abundant isotope, 40 Ca, as well as the rare 46 Ca, are theoretically unstable on energetic grounds, but their decay has not been observed. Calcium also has a cosmogenic isotope, 41 Ca, with half-life 99,400 years. Unlike cosmogenic isotopes that are produced in the air, 41 Ca is produced by neutron activation of 40 Ca. Most of its ...
The Ca 2+ concentration of the vacuole may reach millimolar levels. The most striking use of Ca 2+ ions as a structural element in algae occurs in the marine coccolithophores, which use Ca 2+ to form the calcium carbonate plates, with which they are covered. Calcium is needed to form the pectin in the middle lamella of newly formed cells.
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.
The Americas, as the element was first synthesised on the continent, by analogy with europium: 96: Cm: Curium: Pierre Curie and Marie Curie, French physicists and chemists 97: Bk: Berkelium: Berkeley, California, where the element was first synthesised, by analogy with terbium: 98: Cf: Californium: California, where the element was first ...
The realization that these earths were not elements but compounds is attributed to the chemist Antoine Lavoisier. In his Traité Élémentaire de Chimie (Elements of Chemistry) of 1789 he called them salt-forming earth elements. Later, he suggested that the alkaline earths might be metal oxides, but admitted that this was mere conjecture.