Structure compounds


Not all of the energy produced by photosynthesis in the grass is available to the prairie dog. The grass requires energy to grow and produce structural compounds. Similarly, the prairie dog eats food for the energy it needs for the work of everyday life It needs to find and digest the grass to detect and avoid predators to find a mate and reproduce. Each time one of these processes uses energy, some energy is lost to the environment as heat. By the time the predator eats the prairie dog, vciy little of the original energy from the grass is passed on (Figure 1).  [c.181]

Although organic compounds may be formed from atoms of carbon and other elements, a more restricted class of compounds known as hydrocarbons is made up of carbon and hydrogen atoms only. A broad classification based on structural considerations divides all hydrocarbons into acyclic (open-chain structure) and cyclic (ring structure) compounds which are further divided into certain homologous groups (see Figure 2-76). A simple definition for a homologous series is a family of compounds in which any two successive members differ by a structural unit that is common for the series. The members of such a family show gradual changes in physical properties (e.g., boiling point, melting point, specific gravity, etc.) from one member to the next according to the number of C atoms in the backbone chain.  [c.302]

In certain crystals, e.g. in quartz, there is chirality in the crystal structure. Molecular chirality is possible in compounds which have no chiral carbon atoms and yet possess non-superimposable mirror image structures. Restricted rotation about the C=C = C bonds in an allene abC = C = Cba causes chirality and the existence of two optically active forms (i)  [c.91]

Consequently, each organism depends in some way upon other organisms organisms must interact with each other to survive. For example, a heterotroph must eat other organisms to obtain energy and structural compounds, while many important plant nutrients originate from animal wastes or the decay of dead animals. The study of these interactions is the subject of the science of ecology. Interactions that involve energy transfers between organisms create food chains. A food chain portrays the flow of energy from one organism to another.  [c.181]

Chromium(IJI) oxide. CrjOj (heat on (NH2)2Cr207, hydrolysis and ignition of chromium(lll) compounds). Green compound with the corundum structure. Gives chrom-ates(Ill) in solid stale reactions, anionic species with hydroxyl ions and [Cr(H20)t,P with acids. Used as a green pigment (viridian) and to give green colours in glass and porcelain.  [c.99]

Hammen equation A correlation between the structure and reactivity in the side chain derivatives of aromatic compounds. Its derivation follows from many comparisons between rate constants for various reactions and the equilibrium constants for other reactions, or other functions of molecules which can be measured (e g. the i.r. carbonyl group stretching frequency). For example the dissociation constants of a series of para substituted (O2N —, MeO —, Cl —, etc.) benzoic acids correlate with the rate constant k for the alkaline hydrolysis of para substituted benzyl chlorides. If log Kq is plotted against log k, the data fall on a straight line. Similar results are obtained for meta substituted derivatives but not for orthosubstituted derivatives.  [c.199]

A few metals have more complicated structures (noted under the elements concerned) whilst the structures of the metalloids (semi-metals) are intermediate between those of true metals and homopolar compounds. E.g. germanium and grey tin have the diamond structure arsenic, antimony and bismuth have layer structures, and selenium and tellurium have hexagonal structures containing chains in which each atom has only two neighbours (compare the twelve equidistant neighbours in close-packed structures). Equally, certain alloys and compounds have ail the properties of a metallic element. Bonding in metals is generally considered as being by loss of one or more electrons which form a macroscopic molecular orbital surrounding the close-packed metal ions.  [c.256]

PNXj)/ A group of polymers. The simplest compounds, the chlorides, are formed by heating PCls with NH4CI. Various polymers are known most compounds have cyclic structures as shown but some linear polymers are known. On heating the chlorides to 300 C they are converted to materials possessing some rubber-like properties. The chlorine atoms may be substituted by many other groups. The rings have low hydrolytic stability.  [c.307]

AgaSbSs and silver-copper glance (Cu,Ag)2S). Silver is frequently recovered after the work up of Cu and Pb ores and is generally extracted as a complex cyanide or thiosulphate complex and is recovered by reduction with Zn and purified electrolytically. The metal is a pure white ductile material with a ccp structure, It dissolves in HNO3 3.nd hot cone. H2SO4 but is inert to alkalis. The metal is used extensively in jewellery, electrical components particularly conductors, contacts and batteries, dental and surgical components. It was formerly used extensively in mirrors formed by depositing silver on glass by a reduction process and as a coinage metal. Silver compounds are extensively used in photography and catalysis. World production 1976 9420 tonnes.  [c.360]


See pages that mention the term Structure compounds : [c.38]    [c.38]    [c.40]    [c.42]    [c.43]    [c.55]    [c.58]    [c.59]    [c.60]    [c.74]    [c.75]    [c.92]    [c.98]    [c.102]    [c.110]    [c.116]    [c.119]    [c.120]    [c.136]    [c.151]    [c.205]    [c.207]    [c.215]    [c.218]    [c.225]    [c.226]    [c.250]    [c.257]    [c.263]    [c.276]    [c.292]    [c.294]    [c.295]    [c.301]    [c.307]    [c.310]    [c.317]    [c.331]    [c.345]    [c.358]    [c.363]    [c.366]   
Engineering materials Ч.2 (1999) -- [ c.16 ]