The widely used modern table is essentially the same as Mendeleev's original, except that it has been rotated 90 degrees clockwise (probably for ease of reading) and filled out with newly discovered elements. Small emendations have also been made over the decades. For example, the elements are now ordered not by weight but by the number of protons they have, since that is essentially what determines an element's chemical properties (to turn lead into gold, just remove three protons).

Other problems remain, however. The modern table artificially breaks up the sequence of elements at the end of each row. Certain elements fit into it uncomfortably; for example, hydrogen sits above lithium, with which it shares few properties. And entire groups are relegated to footnotes.

In the eyes of some, the old table is tired and dull-looking. For others, it is precisely the table's minimalism that has given maximum freedom to the imagination. If that plain gray square in the middle, adorned simply with the letters "Au" and the number "79," could represent gold, then what exotica might lurk behind "Rb" (rubidium) or "Mo" (molybdenum)? As Oliver Sacks has written, the periodic table reflects "a deep order in nature [and] the transcendent power of the human mind … to discover or decipher the deepest secrets of nature, to read the mind of God."