The elements which are the most widely diffused have small atomic weights.
Elements which are similar as regards their chemical properties have atomic weights which are either of nearly the same value (eg. Pt, Ir, Os) or which increase regularly (eg. K, Ru, Cs).
We must expect the discovery of many as yet unknown elements-for example, elements analogous to aluminum and silicon- whose atomic weight would be between 65 and 75.
Certain characteristic properties of elements can be foretold from their atomic weights.
The elements, if arranged according to their atomic weights, exhibit an apparent periodicity of properties.
When the elements are arranged in vertical columns according to increasing atomic weight, so that the horizontal lines contain analogous elements again according to increasing atomic weight, an arrangement results from which several general conclusions may be drawn.
The magnitude of the atomic weight determines the character of the element, just as the magnitude of the molecule determines the character of a compound body.