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Multivac is a fictional supercomputer appearing in over a dozen science fiction stories by American writer Isaac Asimov.Asimov's depiction of Multivac, a mainframe computer accessible by terminal, originally by specialists using machine code and later by any user, and used for directing the global economy and humanity's development, has been seen as the defining conceptualization of the genre ...
Melting point: High, since melting means breaking covalent bonds (rather than merely overcoming weaker intermolecular forces). [ 5 ] Solid-phase electrical conductivity : Variable, [ 6 ] depending on the nature of the bonding: network solids in which all electrons are used for sigma bonds (e.g. diamond, quartz) are poor conductors, as there are ...
Like other chlorosilanes or silanes, silicon tetrachloride reacts readily with water: . SiCl 4 + 2 H 2 O → SiO 2 + 4 HCl. The reaction can be noticed on exposure of the liquid to air, as SiCl 4 vapour produces fumes as it reacts with moisture to give a cloud-like aerosol of silica and hydrochloric acid. [6]
In chemistry, a formula unit is the smallest unit of a non-molecular substance, such as an ionic compound, covalent network solid, or metal. [1] [2] It can also refer to the chemical formula for that unit. Those structures do not consist of discrete molecules, and so for them, the term formula unit is used.
"Giant Killer" is a science fiction short story by A. Bertram Chandler. It was first published in the October 1945 issue of Astounding Science Fiction, and later included in many science fiction anthologies, including World of Wonder edited by Fletcher Pratt. [1] In 1996 it was shortlisted for a Retro Hugo Award for Best Novella. [2]
Following periodic trends, its single-bond covalent radius of 117.6 pm is intermediate between those of carbon (77.2 pm) and germanium (122.3 pm). The hexacoordinate ionic radius of silicon may be considered to be 40 pm, although this must be taken as a purely notional figure given the lack of a simple Si 4+
Silicon–oxygen single bonds are longer (1.6 vs 1.4 Å) but stronger (452 vs. about 360 kJ mol −1) than carbon–oxygen single bonds. [1] However, silicon–oxygen double bonds are weaker than carbon–oxygen double bonds (590 vs. 715 kJ mol −1 ) due to a better overlap of p orbitals forming a stronger pi bond in the latter.
In most silicates, silicon atom occupies the center of an idealized tetrahedron whose corners are four oxygen atoms, connected to it by single covalent bonds according to the octet rule. [1] The oxygen atoms, which bears some negative charge, link to other cations (M n+). This Si-O-M-O-Si linkage is strong and rigid, which properties are ...