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Hydrogen in an electrical discharge tube. Hydrogen is a colourless, odourless, and comparatively unreactive diatomic gas with a density of 8.988 × 10 −5 g/cm 3 and is about 14 times lighter than air. It condenses to a colourless liquid −252.879 °C and freezes into an ice- or snow-like solid at −259.16 °C.
Hydrogen is again placed by itself on account of its uniqueness. The remaining nonmetals are divided into metalloids, nonmetals, (referred to as "quintessential nonmetals"), halogens, and noble gases. Since the metalloids abut the post-transition or "poor" metals, they might be renamed as "poor non-metals". [11]
gaseous elements are nonmetals (hydrogen, nitrogen, oxygen, fluorine, chlorine and the noble gases); liquids (mercury, bromine) are either metallic or nonmetallic: mercury, as a good conductor, is a metal; bromine, with its poor conductivity, is a nonmetal; solids are either ductile and malleable, hard and brittle, or soft and crumbly:
Instead, due to hydrogen bonding, water is "stable, potable, odorless, benign, and... indispensable to life". [161] Less well-known of the oxides of hydrogen is the trioxide, H 2 O 3. Berthelot proposed the existence of this oxide in 1880 but his suggestion was soon forgotten as there was no way of testing it using the technology of the time. [162]
In the early work on the chemical composition of the sun the only elements that were detected in spectra were hydrogen and various metals, [41]: 23–24 with the term metallic frequently used when describing them. [41]: Part 2 In contemporary usage all the extra elements beyond just hydrogen and helium are termed metallic.
This line has been called the amphoteric line, [2] the metal-nonmetal line, [3] the metalloid line, [4] [5] the semimetal line, [6] or the staircase. [2] [n 1] While it has also been called the Zintl border [8] or the Zintl line [9] [10] these terms instead refer to a vertical line sometimes drawn between groups 13 and 14.
Liquid helium is used to cool superconducting magnets in modern MRI scanners. Noble gases have very low boiling and melting points, which makes them useful as cryogenic refrigerants . [ 82 ] In particular, liquid helium , which boils at 4.2 K (−268.95 °C; −452.11 °F), is used for superconducting magnets , such as those needed in nuclear ...
Some hydroxides of non-metallic elements are soluble in water; they are not included in the following table. Examples cited by Baes and Mesmer (p. 413) include hydroxides of Gallium(III), Indium(III), Thallium(III), Arsenic(III), Antimony(III) and Bismuth(III). Most hydroxides of transition metals are classified as being "insoluble" in water.