A nonmetal is a chemical element with several properties that are opposite those of a metal. Based on their properties, the elements of the periodic table are generally classified as metals, nonmetals, and metalloids.
Only 18 elements of the periodic table are generally considered nonmetals, whereas more than 80 elements are considered metals. However, nonmetals and their compounds make up most of the crust, atmosphere, and oceans of the Earth, as well as constituting most of the bulk tissues of living organisms.
The elements generally regarded as nonmetals are noted below, along with their groups in the periodic table.
If one looks at their positions in the periodic table, it is clear that almost all the nonmetals (except for hydrogen) are located on the upper right-hand side of the table. They are separated from metals by the group of elements known as metalloids.
Hydrogen, carbon, nitrogen, oxygen, sulfur, and the noble gases can be found in the form of free (uncombined) elements as well as compounds in nature. The other nonmetals occur mainly as compounds. Examples of compounds of nonmetals include the carbonates, nitrates, oxides, sulfides, sulfates, phosphates, and halides.
The Earth's crust, atmosphere, and oceans are constituted mostly of nonmetals and their compounds. Moreover, the bulk tissues of living organisms are composed mainly of nonmetals and their compounds.
There is no rigorous definition for the term "nonmetal"—it covers a general spectrum of behavior. The following are some general properties considered characteristic of nonmetals.
At room temperature, many nonmetals (hydrogen, nitrogen, oxygen, fluorine, chlorine, and the noble gases) are gases; one nonmetal (bromine) is a liquid; the remaining nonmetals are solids. Nonmetals in the gaseous state exist as single atoms or diatomic molecules. By comparison, nearly all metals are solids at room temperature, except for mercury, which is a liquid.
At extremely high pressures, the nonmetals tend to become metallic in nature.
|Standard table | Vertical table | Table with names | Names and atomic masses (large) | Names and atomic masses (small) | Names and atomic masses (text only) | Inline F-block | Elements to 218 | Electron configurations | Metals and non metals | Table by blocks | List of elements by name|
|Groups: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18|
|Periods: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8|
|Series: Alkalis - Alkaline earths - Lanthanides - Actinides - Transition metals - Poor metals - Metalloids - Nonmetals - Halogens - Noble gases|
|Blocks: s-block - p-block - d-block - f-block - g-block|
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