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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.
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.
A mnemonic is a memory aid used to improve long-term memory and make the process of consolidation easier. Many chemistry aspects, rules, names of compounds, sequences of elements, their reactivity, etc., can be easily and efficiently memorized with the help of mnemonics.
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 order of reactivity, as shown by the vigour of the reaction with water or the speed at which the metal surface tarnishes in air, appears to be Cs > K > Na > Li > alkaline earth metals, i.e., alkali metals > alkaline earth metals, the same as the reverse order of the (gas-phase) ionization energies.
An alkalide is a chemical compound in which alkali metal atoms are anions (negative ions) with a charge or oxidation state of −1. Until the first discovery of alkalides in the 1970s, [1] [2] [3] alkali metals were known to appear in salts only as cations (positive ions) with a charge or oxidation state of +1. [4]
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 .
Solvated electrons are involved in the reaction of alkali metals with water, even though the solvated electron has only a fleeting existence. [10] Below pH = 9.6 the hydrated electron reacts with the hydronium ion giving atomic hydrogen, which in turn can react with the hydrated electron giving hydroxide ion and usual molecular hydrogen H 2. [11]