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Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively unreactive.
The pure metallic form was only obtained in 1910 by Matthew A. Hunter. [97] [98] 39 Yttrium: 1794 J. Gadolin: 1843 H. Rose: Johan Gadolin discovered the earth in gadolinite in 1794. He did not name his discovery, but Andreas Ekeberg did so when he confirmed it in 1797. [1] Mosander showed later that its ore, yttria, contained more elements.
This is an accepted version of this page This is the latest accepted revision, reviewed on 17 November 2024. Development of the table of chemical elements The American chemist Glenn T. Seaborg —after whom the element seaborgium is named—standing in front of a periodic table, May 19, 1950 Part of a series on the Periodic table Periodic table forms 18-column 32-column Alternative and ...
For example, germanium was called eka-silicon until its discovery in 1886, and rhenium was called dvi-manganese before its discovery in 1926. The eka-prefix was used by other theorists, and not only in Mendeleev's own predictions. Before the discovery, francium was referred to as eka-caesium, and astatine as eka-iodine.
A recognisably modern form of the table was reached in 1945 with Glenn T. Seaborg's discovery that the actinides were in fact f-block rather than d-block elements. The periodic table and law are now a central and indispensable part of modern chemistry. The periodic table continues to evolve with the progress of science.
E172 would be the end of period 8 ("noble gas") and E173 would be the beginning of period 9. {{ Index by periodic table }} · Category:Hypothetical chemical elements (75) Subtemplates
3rd century: Diophantus uses a primitive form of algebraic symbolism, which is quickly forgotten. [70] 210: Negative numbers are accepted as numeric by the late Han-era Chinese text The Nine Chapters on the Mathematical Art. [71] Later, Liu Hui of Cao Wei (during the Three Kingdoms period) writes down laws regarding the arithmetic of negative ...
41 of the 118 known 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 places on Earth, and the other nine are named after to Solar System objects: helium for the Sun; tellurium for the Earth; selenium for the Moon; mercury (indirectly), uranium, neptunium and plutonium after their respective ...