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Period 2 nonmetals, particularly carbon, nitrogen, and oxygen, show a propensity to form multiple bonds. The compounds formed by these elements often exhibit unique stoichiometries and structures, as seen in the various nitrogen oxides, [ 89 ] which are not commonly found in elements from later periods.
The chemical elements can be broadly divided into metals, metalloids, and nonmetals according to their shared physical and chemical properties.All elemental metals have a shiny appearance (at least when freshly polished); are good conductors of heat and electricity; form alloys with other metallic elements; and have at least one basic oxide.
Nonmetals, including (to a limited extent) xenon and probably radon, usually exist as anions or oxyanions in aqueous solution; they generally form ionic or covalent compounds when combined with metals (unlike metals, which mostly form alloys with other metals); and have acidic oxides whereas the common oxides of nearly all metals are basic.
There are many cases where an element or compound is metallic under certain circumstances, but a nonmetal in others. One example is metallic hydrogen which forms under very high pressures. [44] There are many other cases as discussed by Mott, [4] Inada et al [5] and more recently by Yonezawa. [2]
A chemical bond is the association of atoms or ions to form molecules, crystals, and other structures. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds, or some combination of these effects.
Bettelheim et al. The nonmetals are distinguished based on the molecular structures of their most thermodynamically stable forms in ambient conditions. [5] Polyatomic nonmetals form structures or molecules in which each atom has two or three nearest neighbours (carbon: C x; phosphorus: P 4; sulfur: S 8; selenium: Se x); diatomic nonmetals form molecules in which each atom has one nearest ...
Covalent bonds are generally formed between two nonmetals. There are several types of covalent bonds: in polar covalent bonds, electrons are more likely to be found around one of the two atoms, whereas in nonpolar covalent bonds, electrons are evenly shared. Homonuclear diatomic molecules are purely covalent.
As outlined, ionic bonds occur between an electron donor, usually a metal, and an electron acceptor, which tends to be a nonmetal. [28] Hydrogen bonding occurs when a hydrogen atom bonded to an electronegative atom forms an electrostatic connection with another electronegative atom through interacting dipoles or charges. [29] [30] [31]