Bromine atomic radius

Just as the size of an orbital cannot be specified exactly, neither can the size of an atom. We must make some arbitrary choices to obtain values for atomic radii. These values can be obtained by measuring the distances between atoms in chemical compounds. For example, in the bromine molecule the distance between the two nuclei is known to be 228 pm. The bromine atomic radius... 

Arrange the elements in the following sets in order of decreasing atomic radius (a) lithium, carbon, fluorine (b) scandium, vanadium, iron (c) iron, ruthenium, osmium (d) iodine, bromine, chlorine. 

Compare the elements bromine and chlorine with respect to the following properties (a) electron configuration, (b) most common ionic charge, (c) first ionization energy, (d) reactivity toward water, (e) electron affinity, (f) atomic radius. Accoimt for the differences between the two elements. 

A The covalent radius of bromine is one-half the distance between two bonded bromine atoms. 

Table 8.3 lists selected properties of the first four halogens. Notice that the properties of the halogens, like those of the aUcaU metals, vary fairly regularly as we proceed down the colnmn. As expected from periodic trends, the atomic radius and the density increase for each snccessive halogen. We can see from the melting and boiling points that fluorine and chlorine are both gases at room temperature, bromine is a liquid, and iodine is a solid. 

Bromine crystallizes with a body-centered cubic unit cell. The volume of the unit cell is 0.127 nm . What is its atomic radius ... 

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. 

The van der Waals radius of a methyl group is similar enough to a bromine or iodine atom to make possible isomorphous replacement of terminating methyl groups in lipids. This has been a useful feature for crystal structure determinations. 

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