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The alkali metals dissolve slowly in liquid ammonia, forming ammoniacal solutions of solvated metal cation M + and solvated electron e −, which react to form hydrogen gas and the alkali metal amide (MNH 2, where M represents an alkali metal): this was first noted by Humphry Davy in 1809 and rediscovered by W. Weyl in 1864.
The alkali metals (lithium, sodium, potassium, rubidium, caesium, and francium) are the most homogeneous column of elements in the periodic table, exhibiting very clear periodic trends. All of them are soft and extremely reactive metals, readily giving up their sole valence electron to form cations.
In chemistry, an alkali (/ ˈ æ l k ə l aɪ /; from the Arabic word al-qāly, القلوي) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0.
Lithium metal is soft enough to be cut with a knife. It is silvery-white. In air it oxidizes to lithium oxide. [10] Its melting point of 180.50 °C (453.65 K; 356.90 °F) [13] and its boiling point of 1,342 °C (1,615 K; 2,448 °F) [13] are each the highest of all the alkali metals while its density of 0.534 g/cm 3 is the lowest.
2, but this reaction is accelerated by minute amounts of transition metal salts. [49] Because it can reduce the salts to the metal, potassium is often used as the reductant in the preparation of finely divided metals from their salts by the Rieke method. [50] Illustrative is the preparation of magnesium: MgCl 2 + 2 K → Mg + 2 KCl
Rubidium is the first alkali metal in the group to have a density higher than water. On Earth, natural rubidium comprises two isotopes : 72% is a stable isotope 85 Rb, and 28% is slightly radioactive 87 Rb, with a half-life of 48.8 billion years – more than three times as long as the estimated age of the universe .
The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). [ 1 ] The elements have very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure .
The version of this classification used in the periodic tables presented here includes: actinides, alkali metals, alkaline earth metals, halogens, lanthanides, transition metals, post-transition metals, metalloids, reactive nonmetals, and noble gases. In this system, the alkali metals, alkaline earth metals, and transition metals, as well as ...