. The Becquerel rays and the properties of radium . the same direc-tion. This law is not of sufficient precision to easilyadmit of simple and definite statement. But, broadly,it is this. Let us make a list of the elements in theorder of their atomic weights. Let us also tabulatethe value of some other measurable quality of theelement, such as the melting-point, the boiling-point,or the refraction equivalent. We shall then find that the properties of theclement do not increase regularly with the atomicweight, but they show a regular fluctuation. Everyeighth shows a return to the properties of t
. The Becquerel rays and the properties of radium . the same direc-tion. This law is not of sufficient precision to easilyadmit of simple and definite statement. But, broadly,it is this. Let us make a list of the elements in theorder of their atomic weights. Let us also tabulatethe value of some other measurable quality of theelement, such as the melting-point, the boiling-point,or the refraction equivalent. We shall then find that the properties of theclement do not increase regularly with the atomicweight, but they show a regular fluctuation. Everyeighth shows a return to the properties of the first. PRODUCTS OF EADIO-ACTIYE CHANGE 167 The best and clearest example of this is found, notin the properties ah-eady mentioned, but in the atomicvolume of the element. The late Professor LotharMeyer of Tubingen was the first to draw attention tothe striking periodicity of this property. The atomic volume of an element is defined as thequotient of the atomic weight by the density. If wetake quantities of the different elements in the solid cs. C 20 4€ ec 80 100 120 Atomxt> Weights IW 160 Fig. 27.—Meyers curve, sliowing (lei)en<leiice of atomic volumes on atomic distances represent atomic weights ; vertical ones atomic volumes. Kaclielement is denoted by its cliemieiil symbol. The atomic volume iilternately increases anddiminishes as the atomic weii,ht increiuses. The elements of very high atomic weight :ire notincluded, for there are so lew of tlieiu that the further course of the cuive is not clearlyindicated. state, proportional to their atomic weights, then it isevident that these quantities will each contain anequal number of atoms. Thus the volumes of thesequantities are in the same ratio as the volumes occupied))y their respective atoms. The volume is found bydividing the mass by the density. The quotients of the atomic weights by the re- 1G8 THE BECQUEREL EAYS spective densities are in the same ratio as thevolumes of their atoms, though
Size: 1734px × 1442px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectradioac, bookyear1906
