Periodic Table of Elements

by John R. Carlsen

To facilitate efficient display (and printing) via the World-Wide Web, this version of the periodic table presents atomic chemical element data in a format rotated 90-degrees counterclockwise with respect to traditional presentations. As with most periodic tables, elements in this table are ordered by atomic number (number of protons) and period.

As in Glenn T. Seaborg's extended periodic table, orbitals establish the basis for the groups in this table. Thus, lanthanides and actinides deviate from their prior historical positions as noted. Via the links at top right, orbital blocks may be included or excluded to change the table's size.

Because the period 1 elements – hydrogen (H) and helium (He) – are special cases that do not follow the octet rule, variants of this table accomodate their:

• historic positions (groups 1 and 18),
• orbital-based positions (groups 1 and 2, as in the extended periodic table),
• positions in the Left-Step Periodic Table proposed by Charles Janet in 1928, and
• positions proposed by me (default table) based on accepted rules, using the relative population of their outer orbitals and electronegativity (groups 13 and 18).

The noble gases (group 18) appear at the top of the table and alkali metals (group 1) at the bottom (ordered opposite of those in the simpler mirrored vertical periodic table.)

Data for each element are presented as described in the category and layout legends below.