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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 ...
Transactinide elements – Elements after the actinides (atomic number greater than 103). Transplutonium elements – Elements with atomic number greater than 94. Transuranium elements – Elements with atomic number greater than 92. Valve metal - a metal which, in an electrolytic cell, passes current in only one direction.
[9]: 6 The nitrate can be thermally decomposed to yield the oxide. [9]: 6 Barium metal is produced by reduction with aluminium at 1,100 °C (2,010 °F). The intermetallic compound BaAl 4 is produced first: [9]: 3 3 BaO + 14 Al → 3 BaAl 4 + Al 2 O 3. BaAl 4 is an intermediate reacted with barium oxide to produce the metal. Note that not all ...
An old [12] pound coin (density ~7.6 g/cm 3) floats on mercury due to the buoyancy force upon it and appears to float higher because of the strong surface tension of the mercury. Mercury is a heavy, silvery-white metal that is liquid at room temperature. Compared to other metals, it is a poor conductor of heat, but a fair conductor of ...
The free element is not found in nature, but niobium occurs in combination with other elements in minerals. [40] Minerals that contain niobium often also contain tantalum. Examples include columbite ( (Fe,Mn)Nb 2 O 6 ) and columbite–tantalite (or coltan , (Fe,Mn)(Ta,Nb) 2 O 6 ). [ 47 ]
The metal is highly resistant to corrosion by acids: at temperatures below 150 °C tantalum is almost completely immune to attack by the normally aggressive aqua regia. It can be dissolved with hydrofluoric acid or acidic solutions containing the fluoride ion and sulfur trioxide , as well as with molten potassium hydroxide .
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A once-common use was the making of tetraethyllead and titanium metal; because of the move away from TEL and new titanium production methods, the production of sodium declined after 1970. [60] Sodium is also used as an alloying metal, an anti-scaling agent, [71] and as a reducing agent for metals when other materials are ineffective.