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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.
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]
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:
Sodium metal is highly reducing, with the standard reduction potential for the Na + /Na couple being −2.71 volts, [3] though potassium and lithium have even more negative potentials. [4] The thermal, fluidic, chemical, and nuclear properties of molten sodium metal have caused it to be one of the main coolants of choice for the fast breeder ...
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.
Rubidium oxide – Rb 2 O; Sodium oxide – Na 2 O; Strontium oxide – SrO; Tellurium dioxide – TeO 2; Uranium(IV) oxide – UO 2 (only simple oxides, oxyhalides, and related compounds, not hydroxides, carbonates, acids, or other compounds listed elsewhere)
The alkali metals (Li, Na, K, Rb, Cs, and Fr) are the most reactive metals in the periodic table - they all react vigorously or even explosively with cold water, resulting in the displacement of hydrogen. The Group 1 metal (M) is oxidised to its metal ions, and water is reduced to hydrogen gas (H 2) and hydroxide ion (OH −), giving a general ...