Dictionary of Chemistry [6th Ed.]

towards metal ions, thus giving rise to a series of complexes. phosphorus cycleThe cycling of phosphorus between the biotic and ...

spectra of opaque materials, such as powders, are obtained by exposing the material to light that is modu- lated at acoustic fre ...

tigating the composition of surfaces, based on ionization of atoms at the surfaces. Ionizing radiation (such as X-rays or ultrav ...

sis.) The photolysis of water, using energy from sunlight absorbed by chlorophyll, produces gaseous oxy- gen, electrons, and hyd ...

2H++ 2e–+ NADP+→NADPH + H+. The ATP and NADPH produced dur- ing the light-dependent reactions provide energy and reducing power, ...

phthalic esterAn ester of phthalic acid. Phthalic esters are made by re- acting phthalic anhydride with an al- cohol in the pres ...

piperidineA saturated heterocyclic compound having a nitrogen atom in a six-membered ring, C 5 H 11 N; r.d. 0.86; m.p. –7°C; b.p ...

synthetic resin to make itÛexible. See plastics. plasticsMaterials that can be shaped by applying heat or pressure. Most plastic ...

422 p PLASTICS 1851 Scottish chemist Charles Macintosh (1766–1843) makes ebonite (from rubber). 1855 British chemist Alexander P ...

the polyhedra and single bonds along the edges. In fact, there are only two known Platonic hydrocarbons: cubane (C 8 H 8 ) and d ...

netic properties. Examples are LaSiP 3 , K 6 Bi 2 Sn 23 , and Yb 14 MnSb 11. Com- pounds of this type are known as pnictides. Po ...

electricÜeld p, the polarizability αis deÜned by p= αE. To calculate the polarizability fromÜrst principles it is necessary to u ...

step-wise increase in current is ob- tained. The height of each step is pro- portional to the concentration of the component. Th ...

e.g. polyethene. Sometimes brackets are used in polymer names to in- dicate the repeated unit, e.g. poly(ethene). polyacrylamide ...

oxygen is subjected to a pressure in excess of 1500 atmospheres and a temperature of 200°C. Low-density polyethene (r.d. 0.92) h ...

polystyrene A clear glasslike ma- terial manufactured by free-radical polymerization of phenylethene (styrene) using benzoyl per ...

430 p POLYMERS Polymers are substances that have *macromolecules composed of many repeating units (known as ‘mers’). A large num ...

431 p Heteropolymers These are also known as copolymers. They are made from two (or more) different monomers, which usually unde ...

potash alumSee aluminium potas- sium sulphate; alums. potash micaSee muscovite. potassamideSee potassium monoxide. potassiumSymb ...

gencarbonate, which can then be cal- cined to K 2 CO 3. Potassium carbonate is soluble in water (insoluble in alco- hol) with si ...