Reactivity of Alkaline Earth Metals

The elements occurring in group 2 of the periodic table are alkaline earth metals. These elements are abundant in the earth and thus acquire this name. Group 2 elements have the dipositive oxidation state (M2+) as their primary valence. The alkaline earth metals create mainly ionic compounds but are less ionic than the equivalent alkali metal compounds. This happens because of the greater nuclear charge and smaller size. Beryllium and magnesium oxides and other compounds are more covalent than those generated by the heavier and larger components (Ca, Sr, Ba).

Alkaline earth metals

• Beryllium, magnesium, calcium, strontium, barium and radium are elements in Group 2.
• In the periodic table, they come after alkali metals. Except for beryllium, these are known as alkaline earth metals.
• The first element, beryllium, contrasts from the others in its diagonal interaction with aluminium.
• These elements contain two electrons in the valence shell s-orbital. Their basic electronic configuration is denoted as [noble gas]ns2.
• These elements’ compounds, just as alkali metals, are mostly ionic.
• Alkaline earth metals have a lower reactivity than alkali metals. As we move down the group, the reactivity of such elements rises.

Reactivity of alkaline earth metals

Let us look at the different aspects of reactivity of alkaline earth metals:

Reactivity with water and air

• Because of the creation of an oxide coating on their surfaces, beryllium and magnesium are unresponsive to oxygen and water, so they do not react at all.
• Powdered beryllium, on the other hand, burns excellently in air when ignited, producing BeO and Be3N2.
• Magnesium is highly electropositive and burns brightly in the air to produce MgO and Mg3N2.
• Air quickly affects calcium, strontium and barium to generate oxide and nitride. These also react with intense water, even in freezing temperatures, to produce hydroxides.

Reactivity with halogens

• At high temperatures, most alkaline earth metals interact with halogen to generate their halides.

M + X2 → MX2, where X represents the halogens, including fluorine, bromine, chlorine, and iodine.

• Thermal decomposition of (NH4) 2BeF4 is the best method for producing BeF2, and BeCl2  is easily produced from the oxide. BeO + C + Cl2 —600 to 800 K→ BeCl2 + CO

Reactivity with hydrogen

• Except for beryllium, other elements interact with hydrogen to generate their hydrides, MH2.
• BeH2 , on the other hand, may be created by the reaction of BeCl2 with LiAlH4 2BeCl2 + LiAlH4 → 2BeH2 + LiCl + AlCl3 

Reactivity with acids

• The alkaline earth metals react quickly with acids, releasing dihydrogen.
• A standard reaction expressing the reactivity of metals with acids is given below-

M + 2HCl → MCl2 + H2

Acting as a reducing agent

• Alkaline earth metals, like alkali metals, are powerful reducing agents. This is shown because their reduction potentials have substantial negative values.
• However, their reducing power is lower than that of the comparable alkali metals. Beryllium has a lower negative value than other alkaline earth elements.
• However, its reducing character is due to the high hydration energy attributed to the tiny size of the Be2+ ion and the comparatively large value of the metal’s atomisation enthalpy.

Reaction with liquid ammonia

• Alkaline earth metals, just as alkali metals, break down in liquid ammonia to generate deep blue-black solutions containing ammoniated ions.
• Ammoniates are recovered through these solutions.

Uses of alkaline earth metals

• Beryllium is a metal that is utilised in the production of alloys.
• Copper-beryllium alloys are used to make strong springs.
• Metallic beryllium is adopted to make X-ray tube windows. Magnesium may be found in aluminium, zinc, manganese and tin alloys.
• Because magnesium-aluminium alloys are low in weight, they are helpful in manufacturing aircraft.
• Magnesium (powder and ribbon) is often included in flash powders and bulbs and incendiary explosives and signals.
• A suspension of magnesium hydroxide in water (known as milk of magnesia) is often useful as an antacid in medicine. Magnesium carbonate is found in toothpaste.
• Calcium is employed in the extraction of metals from challenging oxides with carbon.
• Because of their reactivity with oxygen and nitrogen at high temperatures, calcium and barium metals have frequently been utilised to extract air from vacuum tubes.
• Radium salts are used in radiation to cure cancer patients, for instance.

Conclusion

The group, two elements of the periodic table, are known as alkaline earth metals. They possess two electrons in their valence shell. Alkaline earth metals are highly reactive elements. The behaviour of alkaline earth metals is similar to that of alkali metals. However, there are distinctions since alkaline earth metals have smaller atomic and ionic sizes and higher cationic charges. Their oxides and hydroxides are less basic than those of alkali metals.