S-Block Elements Test - 15

High hydration enthalpy of BeSO₄ overpowers its lattice enthalpy thus is water soluble.

Alkaline earth metal nitrates are prepared in solution and can be crystallized as hydrated salt by the action of HNO₃ on oxides ,hydroxides and carbonates.

MO + 2 HNO₃ ——> M(NO₃)₂ + H₂O

M(OH)₂ + 2 HNO₃ ———> M(NO₃)₂ + 2 H₂O

MCO₃ + 2 HNO₃ ———> M(NO₃)₂ + H₂O + CO₂ 

Tendency to form hydrates decreases with increasing size and decreasing hydration enthalpy down the group.

All nitrates are soluble in water and decompose on heating to give the corresponding oxides with evolution of NO₂ and O₂.

Strontium and barium nitrate are used in pyrotechnics for giving red and green flames.

BeCl₂ + LiAlH⁴ give 2BeH₂ + LiCl and AlCl₃
However, other elements of group 2 combine with hydrogen upon heating to form MH₂

Solubility of an ionic compound in water depends upon lattice energy of compound and hydration energy of ions.

All the alkali metals have an electron in their outermost shell and all the alkaline earth metals have two outer electrons. To achieve the noble gas configuration, alkali metals need to lose one electron (valence is “one”), whereas alkaline earth metals need to remove two electrons (valence is “two”).

Cesium is an alkali metal, like sodium; hence, it forms a salt, cesium chloride (CsCl) similar to table salt, sodium chloride.CsCl looks like most salts:It's worth noting that the formation of salts is highly exothermic, that is, if you were to get cesium metal and gaseous chlorine to combine to form this salt, the reaction would produce a lot of heat along the way!

Among alkali metals, melting point decreases as the strength of metallic bonding decreases with increasing size of the atom. Thus, Cs has the lowest melting point (28.5°C) and will melt at 30°C.

This alkaline earth hydride is a colourless solid that is insoluble in solvents that do not decompose it. Unlike the ionically bonded hydrides of the heavier Group 2 elements, beryllium hydride is covalently bonded (three-center two-electron bond).

The oxidation state of superoxide is -1/2 . and there is two superoxide so oxidation state of Rb is +1.

Alkaline earth metals have valency +2. So on reaction with halogen, they form compounds MX₂.