<Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> 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). Elements to the lower left of the line generally display increasing metallic behaviour; elements to the upper right display increasing nonmetallic behaviour . 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 . </P> <P> This line has been called the amphoteric line, the metal - nonmetal line, the metalloid line, the semimetal line, or the staircase . It is also erroneously referred to as the Zintl border or the Zintl line . The last two terms instead refer to a vertical line sometimes drawn between groups 13 and 14 . This particular line was christened by Laves in 1941 . It differentiates group 13 elements from those in and to the right of group 14 . The former generally combine with electropositive metals to make intermetallic compounds whereas the latter usually form salt - like compounds . </P> <P> References to a dividing line between metals and nonmetals appear in the literature as far back as at least 1869 . In 1891, Walker published a periodic' tabulation' with a diagonal straight line drawn between the metals and the nonmetals . In 1906, Alexander Smith published a periodic table with a zigzag line separating the nonmetals from the rest of elements, in his highly influential textbook Introduction to General Inorganic Chemistry . In 1923, Horace G. Deming, an American chemist, published short (Mendeleev style) and medium (18 - column) form periodic tables . Each one had a regular stepped line separating metals from nonmetals . Merck and Company prepared a handout form of Deming's 18 - column table, in 1928, which was widely circulated in American schools . By the 1930s Deming's table was appearing in handbooks and encyclopaedias of chemistry . It was also distributed for many years by the Sargent - Welch Scientific Company . </P>

In the periodic table the elements that are adjacent to the stair step are called