The dividing line between metals and nonmetals can be found, in varying configurations, on some representations of the periodic table of the elements (see mini-example, right).
When presented as a regular stair-step, elements with the highest critical temperature for their groups (Li, Be, Al, Ge, Sb, Po) lie just below the line.
[14] In 1906, Alexander Smith published a periodic table with a zigzag line separating the nonmetals from the rest of elements, in his highly influential[15] textbook Introduction to General Inorganic Chemistry.
[16] In 1923, Horace G. Deming, an American chemist, published short (Mendeleev style) and medium (18-column) form periodic tables.
[23][n 2][n 3] Several other sources note confusion or ambiguity as to the location of the dividing line;[26][27] suggest its apparent arbitrariness[28] provides grounds for refuting its validity;[29] and comment as to its misleading, contentious or approximate nature.