Mrs Roberts: Well, the modern periodic table shows us all of the elements arranged in rows, which are called periods. It has changed a lot over the years as we've learned more and more about atoms.

The modern periodic table is based closely on the ideas he used. These ideas were: The elements are arranged in order of increasing atomic mass The horizontal rows are called periods The vertical ...

The periodic table of chemical elements, often called the periodic table, organizes all discovered chemical elements in rows (called periods) and columns (called groups) according to increasing atomic ...

As part of the ChemClub's 10 th Anniversary, we asked clubs to create elements of the periodic table featuring a mole. The Period Table of Endangered Elements presents elements facing supply ...