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In the context of the periodic table a nonmetal is a chemical element that mostly lacks distinctive metallic properties. They range from colorless gases like hydrogen to shiny crystals like iodine. Physically, they are usually lighter (less dense) than elements that form metals and are often poor conductors of heat and electricity.
In 1891, Walker published a periodic "tabulation" with a diagonal straight line drawn between the metals and the nonmetals. [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]
Periodic table of the chemical elements showing the most or more commonly named sets of elements (in periodic tables), and a traditional dividing line between metals and nonmetals. The f-block actually fits between groups 2 and 3 ; it is usually shown at the foot of the table to save horizontal space.
Some nonmetals (black P, S, and Se) are brittle solids at room temperature (although each of these also have malleable, pliable or ductile allotropes). From left to right in the periodic table, the nonmetals can be divided into the reactive nonmetals and the noble gases. The reactive nonmetals near the metalloids show some incipient metallic ...
Periodic table extract showing the location of the post-transition metals. Zn, Cd and Hg are sometimes counted as post-transition metals rather than as transition metals. The dashed line is the traditional dividing line between metals and nonmetals. The symbols for the elements commonly recognized as metalloids are in italics. The status of ...
Recognition status, as metalloids, of some elements in the p-block of the periodic table. Percentages are median appearance frequencies in the lists of metalloids. [n 1] The staircase-shaped line is a typical example of the arbitrary metal–nonmetal dividing line found on some periodic tables.
The term is sometimes also used when describing dopants of specific elements types in compounds, alloys or combinations of materials, using the periodic table classification. For instance metalloids are often used in high-temperature alloys, [29] and nonmetals in precipitation hardening in steels and other alloys. [30]
The s-block, with the s standing for "sharp" and azimuthal quantum number 0, is on the left side of the conventional periodic table and is composed of elements from the first two columns plus one element in the rightmost column, the nonmetals hydrogen and helium and the alkali metals (in group 1) and alkaline earth metals (group 2).