Dictionary of Chemistry [6th Ed.]

between the levels 2p^10 and 5d^5 of the nuclide krypton–86. This deÜni- tion (in 1958) replaced the older deÜ- nition of a metr ...

capable of weighing masses of the order 10–6to 10–9kg. microcrystal test See crystal test. microscopic Designating a size scale ...

crystalline structure. The term is also often applied generally to organic substances that are obtained by min- ing (e.g. coal, ...

the French chemist Henri Moissan (1852–1907), who discovered it in 1893. molal concentrationSee concen- tration. molalitySee con ...

vated complex in a step of a chemical reaction. Reactions are said to be uni- molecular, bimolecular, or trimolecu- laraccording ...

analysed systematically using *group theory. It is possible to make deÜnite statements about certain properties of molecules, su ...

metry it is a spherical top. If it has a threefold or higher axis of symmetry it is a symmetric top. If it does not have a three ...

include calculations in the theory of liquids, phase transitions, and quan- tum mechanical systems. The name comes from the casi ...

where r is the variable interatomic distance and reis the equilibrium in- teratomic distance. The Morse poten- tial U(r – re) is ...

multidecker sandwichSee sand- wich compound. multiple bondA bond between two atoms that contains more than one pair of electrons ...

mustard gas See sulphur mustard; nitrogen mustard. mutarotation Change of optical activity with time as a result of spon- taneou ...

N NAD(nicotinamide adenine dinu- cleotide)A coenzyme, derived from the B vitamin nicotinic acid, that participates in many biolo ...

napalmA substance used in incen- diary bombs andÛame throwers, made by forming a gel of petrol with aluminium soaps (aluminium s ...

Néel temperature The tempera- ture above which an antiferro- magnetic substance becomes paramagnetic (see magnetism). The suscep ...

neptunium seriesSee radioactive series. Nernst, (Hermann) Walther (1864–1941) German physical chemist noted for his work on elec ...

stable in the atomic nucleus but de- cays into a proton, an electron, and an antineutrino with a mean life of 12 minutes outside ...

cous it becomes. This property is used in nondrip paints (which are more viscous on the brush than on the wall) and in lubricati ...

potassium hydroxide. The reaction on discharge is 2NiOOH.H 2 O + Fe →2Ni(OH) 2 + Fe(OH) 2 , the reverse occurring during charg- ...

also used in forensic science to de- velop latentÜngerprints. niobiumSymbol Nb. A soft ductile grey-blue metallic transition el- ...

tric acid is a strong oxidizing agent. Most metals dissolve to form nitrates but with the evolution of nitrogen oxides. Concentr ...