nonlogam

Nonlogam is a term used in some languages to designate nonmetals, the chemical elements that do not exhibit metallic properties. In this usage, nonlogams include hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, selenium, the halogens, and the noble gases, and they are contrasted with metals (logam) and metalloids. The term helps categorize elements by common physical and chemical traits rather than by location alone on the periodic table.

Typical properties of nonlogams include poor electrical and thermal conductivity (with notable exceptions such as graphite, a form of carbon, which conducts electricity better than most nonmetals). They generally have lower densities than metals and higher electronegativities and ionization energies. Most nonlogams form covalent bonds and tend to create oxides that are acidic or neutral rather than basic. Elemental forms vary widely: diatomic molecules such as H2, N2, O2, F2, and Cl2; solid carbon in the forms of graphite and diamond; sulfur and phosphorus as brittle solids; and the noble gases as inert, monatomic gases under standard conditions.

Applications and significance are broad. Carbon underpins organic chemistry and biology; nitrogen and oxygen are essential to life and global biogeochemical cycles; halogens are highly reactive and used in chemistry and disinfection; noble gases have specialized roles in lighting, cryogenics, and inert atmospheres. Nonlogams are often contrasted with metals and with metalloids, which exhibit intermediate properties between the two groups. In many contexts, nonlogam remains a practical label for the class of elements that do not display metallic characteristics.