Harkin’s rule

Harkins s rule of the dissymmetry between even-odd nuclei is sometimes referred to as the Oddo-Harkins rule. In 1914 the Italian chemist Guiseppe Oddo suggested that elements with atomic weights a multiple of... 

Promethium is a typical element of the lanthanide series. The relative abundances of the lanthanides are plotted in Fig. 14.1 as a function of the atomic number. This figure illustrates Harkin s rule the abundance of elements with even atomic numbers is appreciably higher than that of elements with odd atomic numbers. For element 61 the natural abundance is zero. 

All actinides are radioelements and only Th and U have half-lives long enough to justify neglecting their radioactivity in some special chemical or technical operations. Ac and Pa are present in small amounts as decay products of U and Th (Table 11.3). Extremely small amounts of Np and Pu are produced in U by neutrons from cosmic radiation 10 1, Pu/ U 10" " 1. Harkin s rule is... 

In the whole universe, elements with even atomic numbers are more common than their nearest neighbors with odd atomic numbers. This phenomenon is known as Harkin s rule. An important exception is hydrogen, which undoubtedly has the odd number 1, but nevertheless is the most common element in the universe. This is a consequence of the proton s important function in the building-up of heavier nu-... 

Some interesting conclusions may be drawn from a consideration of the magnitude of the interfacial surface tensions of various liquids. The significance of these was first pointed out by Hardy Froc. Roy. Soc. A, Lxxxviii. 303, 1913) and emphasised by Harkins J.A.G.S. XXXVIII. 228,1916 xlil 700,1920). We have noted that Antonow s rule only applies to mutually saturated solutions. If two... 

If we have E >0 and S = 0, then a drop of oil on the surface of a liquid will in principle be spread over that surface to form a duplex flhn at equilibrium (obeying Antonow s rule [20]). In contradiction Harkins [18] has claimed that 5 < 0 always prevails at equilibrium even if the initial spreading coefficient 5 > 0. However, Rowlinson and Widom [19] emphasize convincingly that. S = 0 is allowed so that stable duplex films can often be found between mutually saturated liquids at equilibrium. 

It is observed that the abundance decreases with increasing atomic number Z HREEs are much less abundant than LREEs. What s more, according to the Oddo-Harkins Rule, elements with an even atomic number are more abundant than elements with an odd atomic number. For instance, cerium (Z = 58) is more abundant than lanthanum (Z = 57) and praseodymium (Z = 59). Cerium is the dominating rare earth in the LREE, whereas Y is the dominant rare earth in the HREE (Binnemans et al. 2013). 

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