Chlorine radius

A portion of the effluent is recirculated, ia order to smooth out flow, keep the food concentration constant, lower film thickness and control psychoda flies, and reseed the appHed sewage with acclimatized organisms. The psychoda, or filter fly is a very small iasect that breeds ia thick trickling-filter slimes. It does not bite, but can be a nuisance. Its radius of flight is small, but it can be carried great distances by the wiad. The fly can be controlled ia the development phase by occasional flooding of the filter or chlorination of the appHed sewage. 

Atomic radii. The radii are determined by assuming that atoms in closest contact in an element touch one another. The atomic radius is taken to be one half of the closest internuclear distance, (a) Arrangement of copper atoms in metallic copper, giving an atomic radius of 0.128 nm for copper, (b) Chlorine atoms in a chlorine (Cl2) molecule, giving an atomic radius of 0.099 nm for chlorine. 

When chlorine, CU, is examined in a mass spectrograph, Cl/, Cl+, and Cl+I ions are formed. Remembering that there are two isotopes in chlorine, 35 (75%) and 37 (25%), describe qualitatively the appearance of the mass spectrum. Which ion will produce lines at the largest radius Which at the smallest radius How many lines will each ion produce ... 

Arrange the elements in each of the following sets in order of decreasing atomic radius (a) sulfur, chlorine, silicon ... 

The high-temperature contribution of vibrational modes to the molar heat capacity of a solid at constant volume is R for each mode of vibrational motion. Hence, for an atomic solid, the molar heat capacity at constant volume is approximately 3/. (a) The specific heat capacity of a certain atomic solid is 0.392 J-K 1 -g. The chloride of this element (XC12) is 52.7% chlorine by mass. Identify the element, (b) This element crystallizes in a face-centered cubic unit cell and its atomic radius is 128 pm. What is the density of this atomic solid ... 

Figure 5.2 (a) Electron density contour map of the CI2 molecule (see Chapter 6) showing that the chlorine atoms in a CI2 molecule are not portions of spheres rather, the atoms are slightly flattened at the ends of the molecule. So the molecule has two van der Waals radii a smaller van der Waals radius, r2 = 190 pm, in the direction of the bond axis and a larger radius, r =215 pm, in the perpendicular direction, (b) Portion of the crystal structure of solid chlorine showing the packing of CI2 molecules in the (100) plane. In the solid the two contact distances ry + ry and ry + r2 have the values 342 pm and 328 pm, so the two radii are r 1 = 171 pm and r2 = 157, pm which are appreciably smaller than the radii for the free CI2 molecule showing that the molecule is compressed by the intermolecular forces in the solid state. 

Chapter 6. The outer contour in this map is for a density of 0.001 au, which has been found to represent fairly well the outer surface of a free molecule in the gas phase, giving a value of 190 pm for the radius in the direction opposite the bond and 215 pm in the perpendicular direction. In the solid state molecules are squashed together by intermolecular forces giving smaller van der Waals radii. Figure 5.2b shows a diagram of the packing of the Cl2 molecules in one layer of the solid state structure of chlorine. From the intermolecular distances in the direction opposite the bond direction and perpendicular to this direction we can derive values of 157 pm and 171 pm for the two radii of a chlorine atom in the CI2 molecule in the solid state. These values are much smaller than the values for the free molecule in the gas phase. Clearly the Cl2 molecule is substantially compressed in the solid state. This example show clearly that the van der Waals of an atom radius is not a well defined concept because, as we have stated, atoms in molecules are not spherical and are also compressible. 

A covalent radius is the radius of an atom that is bonded covalently to another. For example, one half the intemuclear distance in Cl, is the covalent radius of chlorine. A metallic radius is half the shortest intemuclear distance in a crystal of solid metal. 

The Dp and Dq are the diffusion coefficients of probe and quencher, respectively, N is the number molecules per millimole, andp is a factor that is related to the probability of each collision causing quenching and to the radius of interaction of probe and quencher. A more detailed treatment of fluorescence quenching including multiexponential intensity decays and static quenching is given elsewhere/635 There are many known collisional quenchers (analytes) which alter the fluorescence intensity and decay time. These include O2/19 2( 29 64 66) halides,(67 69) chlorinated hydrocarbons/705 iodide/715 bromate/725 xenon/735 acrylamide/745 succinimide/755 sulfur dioxide/765 and halothane/775 to name a few. 

Bromine has an ionic radius of 1.96 A and thus easily substitutes for chlorine (1.81 A) in the halite crystal lattice as well as in the other chloride salts. The distribution coefficients for bromine in chloride salts deposited from seawater is less than 1 (Warren 2006). 

The Arw and AVW are the van der Waals radius of the atom of substituents directly bound to the ring and the van der Waals molar volume of substituents, respectively, those of the chlorine substituent being taken as reference. 

If one could determine the ionic radius of one single element, then the values for the other elements would be known. Assuming that the radius of the chlorine atom is 1-81 A, then, from the shortest distance between two particles in KC1, for which the value 3 14 A has been found, the radius of the K+ ion is 1 - 33 A, and, similarly, from the shortest distance in KBr is obtained the radius of bromine, and so on. The determination of the single radius is made in the following manner. 

In the diagram the elements displace the elements in the compounds to their left because the former have a lower charge, and an element displaces the one below it because it has a smaller radius. If we now proceed further and inquire what reaction occurs between chlorine and an oxide, and vice versa, we cannot say exactly what will happen. Chlorine has the advantage of a smaller ionic charge while the oxygen has the smaller radius. In the reaction between oxygen and hydrochloric acid... 

In a molecule of chlorine, with the electronic structure Cl Cl , the covalent radius of chlorine may be described as representing roughly... 

The van der Waals radius is expected to be larger than the covalent radius, since it involves the interposition of two electron pairs between the atoms rather than one. Moreover, the van der Waals radius of chlorine should be about equal to its ionic radius, inasmuch as the bonded atom presents the same face to the outside world in directions... 

The ionic radius of chlorine has the value 1.81 A (Chap. 13). The following distances between chlorine atoms of different molecules have been observed in the molecular crystal 1,2,3,4,5,(Whexachlorocyclo-hexane.-57 3,60, 3.77, 3.82 A these are close to twice the ionic radius. Similar agreement is shown by many other organic crystals and inorganic covalent crystals. Cadmium chloride, for example, consists of... 

Waals radii. In carbon tetrachloride the chlorine atoms are only 2.87 A apart, and yet the properties of the substance indicate that there is no great strain resulting from the repulsion that should correspond to the van der Waals diameter 3.6 A. Even in methylene chloride and chloroform, where the strain might be relieved bv increasing the bond angle, the chlorine-chlorine distance is only 2.92 A. We conclude that the nonbonded radius of an atom in directions close to the bond direction (within 35°) is about 0.5 A less than the van der Waals radius a unicovalent atom can be considered as a sphere that is whittled down on the side of the bond. 

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