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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 ...
Roman numerals: for example the word "six" in the clue might be used to indicate the letters VI; The name of a chemical element may be used to signify its symbol; e.g., W for tungsten; The days of the week; e.g., TH for Thursday; Country codes; e.g., "Switzerland" can indicate the letters CH; ICAO spelling alphabet: where Mike signifies M and ...
Niobium is a chemical element; it has symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and ductile transition metal. Pure niobium has a Mohs hardness rating similar to pure titanium, [8] and it has similar ductility to iron.
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.
Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium. [68] About 0.9% of the Sun's mass is oxygen. [19] Oxygen constitutes 49.2% of the Earth's crust by mass [69] as part of oxide compounds such as silicon dioxide and is the most abundant element by mass in the Earth's crust.
Einsteinium is a synthetic chemical element; it has symbol Es and atomic number 99. It is named after Albert Einstein and is a member of the actinide series and the seventh transuranium element . Einsteinium was discovered as a component of the debris of the first hydrogen bomb explosion in 1952.
The 3.8-day half-life of 222 Rn makes it useful in physical sciences as a natural tracer. Because radon is a gas at standard conditions, unlike its decay-chain parents, it can readily be extracted from them for research. [20] It is inert to most common chemical reactions, such as combustion, because the outer valence shell contains eight electrons.
A chemical element is a chemical substance whose atoms all have the same number of protons. The number of protons is called the atomic number of that element. For example, oxygen has an atomic number of 8, meaning each oxygen atom has 8 protons in its nucleus.