how the periodic table works?
The periodic table is arranged by atomic number (number of protons in the nucleus) rather than atomic mass, but the effect is the same, because the mass increases as the atomic number increases. So it is far from coincidence that the atomic mass increases as you go down the group columns. [Jan 26 04 9:27 AM] Gnomon writes: The reason the elements are divided into groups is because of the quantum mechanical limitations of the electron orbitals. At the first energy level, there is only one orbital, the 1s. This can take two electrons, so there are two elements in the first row of the table. The 2nd energy level can take 8 electons in four orbitals, the 2s, 2p1, 2p3 and 2p3 orbitals. So there are 8 elements in the second row. The elements in the first row are positioned directly above the ones in the second row which match their properties closest. The third energy level is the same as the 2nd; it can hold 8 electrons, so this row corresponds to the second.
