The elements have "similar" chemistry as lithium.
They all give away an electron to form ionic compounds. The only difference is the increasing ease with which the element will give off the electron with increasing size. This is to be expected as the influence of the protons on the valence electron decreases with distance. This is shown by the decrease in ionisation potential from Na to Rb.
All ionic compounds are soluble in polar solvents. The only difference is the solubility decreases with increasing size of the cation ion. This is also to be expected as the charge density (defined as amount of charge per unit surface area of the ion) decreases with the size of the ion. The net positive charge for the alkali ion is always 1. With decrease in surface charge density the strength of the electrostatic interaction with the polar solvent will naturally decrease.
REACTION WITH OXYGEN
Lithium reacts with oxygen to give lithium oxide, Li2O. The other members (or congeners) react to give the peroxide, M2O2.
The peroxides are readily hydrolysed to give the hydroxides.
Peroxides are not very stable at room temperature and decompose by itself:
The peroxides are also readily hydrolysed to give the hydroxides.
Atomic oxygen is a very powerful oxidizing agent and a great disinfectant. Some detergents contain added compounds that can release atomic oxygen to decompose stubborn dirt. The oxygen atom can also recombine to give the oxygen molecule.
REACTION WITH WATER
Of course the metals can also react directly with water to give the hydroxide. However, while the reaction with lithium is mild, the reactivity increases down the Group. With potassium it becomes explosive.
The hydroxides can then react with all acids to give the corresponding salts.
All the salts are soluble in water but the solubility decrease with the size of the cation and the size of the anion. So cesium perchlorate, Cs(ClO4), is not very soluble in water.
SOLUBILITY in AMMONIA, AMINES and ETHERS
The metals dissolve in ammonia, amines and ethers. Example, lithium in methylamine (CH3NH2) or ethylenediamine (NH2CH2CH2NH2), or sodium in ammonia. The solution can then be used (example by heating) to release atomic hydrogen.
Atomic hydrogen [H] is very reactive and can add onto pi-bond very easily.
Note: Do not worry if you do not know what amines are. We will come to it in Organic Chemistry. For the time being just know that they are RNH2 compounds, where R is an alkyl group.REACTION WITH MERCURY
All Group 1A elements will dissolve in mercury to form amalgams. Sodium amalgam is very often used as reducing agents in chemistry.
REACTION WITH ORGANIC COMPOUNDS
The organo compounds of the other elements are not as important as that of lithium.
