Encyclopedia of Chemistry

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NAD+ Oxidized form of nicotinamide adenine dinu- cleotide. Note that despite the plus sign in the symbol, the COENZYMEis anionic ...

occurring radioactive substances, e.g., C-14, K-40, U, and Th and some of their decay products. NCE SeeNEW CHEMICAL ENTITY. NDA( ...

nickel-cadmium cell(nicad battery) A dry cell in which the anode is cadmium (Cd), the cathode is NiO 2 , and the electrolyte is ...

noble gases (rare gases) All the elements of the peri- odic Group 0; also called rare gases; formerly called inert gases: helium ...

nuclear decay Disintegration of atomic nuclei that results in the emission of ALPHAor BETA PARTICLEs (usually with gamma radiati ...

See alsoGENETIC CODE; MESSENGERRNA; OLIGONU- CLEOTIDE; RIBONUCLEIC ACID; RIBOSOMALRNA. nucleobase SeeNUCLEOSIDE. nucleofuge A LE ...

nucleophilic catalysis CATALYSISby a LEWIS BASE, involving formation of a LEWIS ADDUCTas a REACTION INTERMEDIATE. For example, t ...

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obligate aerobe Any organism that must utilize atmospheric oxygen in its metabolic pathways and for cellular respiration, and ca ...

ODMR SeeOPTICALLY DETECTED MAGNETIC RESO- NANCE. OEC SeeOXYGEN-EVOLVING COMPLEX. oil A slippery, viscous, or liquefiable substan ...

optical isomers(enantiomers) Are nonsuperimpos- able mirror images of each other and are said to be chi- ral (not superimposable ...

REACTIONs are likely to occur under thermal or photo- chemical conditions. See alsoSIGMA, PI. order of reaction n(SI unit: 1) If ...

carbon, hydrogen, oxygen, and nitrogen atoms bonded together. Organic chemistry is one of two main divi- sions of chemistry, the ...

outer-sphere electron transfer An outer-sphere elec- tron transfer is a reaction in which the electron transfer takes place with ...

that would remain on a given atom if the pairs of elec- trons in each bond to that atom were assigned to the more electronegativ ...

Oxygen, chlorine, ozone, and peroxide compounds are examples of oxidizing agents. oxidoreductase An ENZYME of EC class 1, which ...

pairing energy Energy required to place two elec- trons in the same orbital. See alsoATOMIC ORBITAL; MOLECULAR ORBITAL. paraffin ...

to one newton (1 N) of force applied over an area of one meter squared (1 m^2 ). passivation Describes the state where metals or ...

Group III elements are B, Al, Ga, In, and Tl. Their outer electron configuration is s 2 p1. Group IV contains the elements C, S ...