Dictionary of Chemistry [6th Ed.]

tures and observe single atoms. A Üne-pointed conducting tip near a surface of a sample causes electrons to tunnel from the surf ...

hedral groups T, Th, and Td, the octa- hedral groups O and Oh, and the icosahedral group I. The SchoenÛies system is commonly us ...

secondary-ion mass spectrom- etry(SIMS)A technique for ana- lysing the chemical structure of a solid by bombarding it with ions. ...

tion states. Selenium was discovered in 1817 by Jöns Berzelius. A Information from the WebElements site selenium cellEither of ...

arating ketones from reaction mix- tures: the derivative is crystallized out and hydrolysed to give the ke- tone. A Information ...

terials, such as gallium arsenide, are suitable for this purpose. A junction between p-type and n-type semicon- ductors can be u ...

of destructive interference, the pho- toelectron has a lower probability of appearing. The technique therefore provides informat ...

–185°C; b.p. –112°C. Silane is pro- duced by reduction of silicon with lithium tetrahydridoaluminate(III). It is also formed by ...

silicon 482 s silicides are structurally similar to the interstitial carbides but the range encountered is more diverse. They re ...

curring in various forms of silicon(IV) oxide (e.g. quartz) and in silicate minerals. The element is extracted by reducing the o ...

silverSymbol Ag. A white lustrous soft metallic *transition element; a.n. 47; r.a.m. 107.87; r.d. 10.5; m.p. 961.93°C; b.p. 2212 ...

Simon test A *presumptive test for methamphetamines. The Simon reagent consists of 1 gram of sodium nitroprusside (Na 2 Fe(CN) 5 ...

ore is smelted in this way so that the metal melts and, being denser than the molten *slag, sinks below the slag, enabling it to ...

soda ashAnhydrous *sodium car- bonate, Na 2 CO 3. soda limeA mixed hydroxide of sodium and calcium made by slaking lime with cau ...

sodium bicarbonateSee sodium hydrogencarbonate. sodium bisulphateSee sodium hydrogensulphate. sodium bisulphiteSee sodium hy- dr ...

with the iron in haemoglobin in the blood, so preventing oxygen reaching the tissues of the body. It is used in the extraction o ...

very slightly soluble in water; r.d. 2.9; m.p. 1000°C. It changes to a cubic form at 580°C. The compound occurs naturally as the ...

tion of wine casks. It is a general an- tiseptic and bleaching agent. See also aldehydes. sodium hydroxide (caustic soda) A whit ...

mal decomposition of sodium nitrate and is used in the preparation of ni- trous acid (reaction with cold dilute hydrochloric aci ...

count of its reducing properties. It has also been used for the production of sodium thiosulphate (for the pho- tographic indust ...