墨尔本PTE 阅读排序 2965

A. The modern periodic table lists the elements in order of increasing atomic number (the number of protons in the nucleus of an atom).   

B. Nevertheless, the basis of the modern periodic table was well established and even used to predict the properties of undiscovered elements long before the concept of the atomic number was developed.   

C. Chemists have always looked for ways of arranging the elements to reflect the similarities between their properties.   

D. This was mainly because the idea of atoms being made up of smaller sub-atomic particles (protons, neutrons and electrons) had not been developed.   

E. Historically, however, relative atomic masses were used by scientists trying to organise the elements.