The group 1 elements of the periodic table, except hydrogen, are alkali metals, and the group two elements, except beryllium, are alkaline earth metals. The s-block elements have a typical electronic configuration of ns1 for alkali metals and ns2 for alkaline earth metals.  Because of charge and the addition of an electron to the same energy level, both ionic and atomic radii fall along the periodic table column, making them smaller than alkali metals and more prominent than other atoms of the same period. Both s-electrons can be lost in alkaline earth elements, making them doubly positive cationic. A cationic atom has a smaller radius than a neutral atom. Moving down the column, the ionic radii increase.

s-block elements

• The periodic table’s s-block elements are those in which the last electron reaches the outermost s-orbital.
• Because the s-orbital can only hold two electrons, the s-block of the periodic table constitutes two groups.
• The elements in group 1 of the periodic table include lithium, sodium, potassium, rubidium, caesium, and francium. They are called alkali metals since when they react with water, the metals generate very alkaline hydroxides.
• Group 2 elements comprise beryllium, magnesium, calcium, strontium, barium, and radium. Apart from beryllium, all group 2 elements are classified as alkaline earth metals as their oxides and hydroxides are alkaline and are obtained from the earth’s crust.

Alkaline Earth Metals

• Beryllium, magnesium, calcium, strontium, barium, and radium are members of group 2.
• In the periodic table, they come after alkali metals. Except for beryllium, the elements in group 2 are called alkaline earth metals.
• The first element, beryllium, varies from the others in that it has a diagonal interaction with aluminium.
• These elements contain two electrons in the outermost shell s-orbital.
• Their typical electronic configuration may be written as [noble gas]ns2.
• In general, alkaline earth metals are silvery-white, shiny, and somewhat soft but firmer than alkali metals. Beryllium and magnesium possess a light grey colour.
• Because of their smaller sizes, these metals have greater melting and boiling points than the comparable alkali metals. The tendency, though, is not consistent.
• They are very electropositive due to their low ionisation enthalpies. From Be to Ba, the electropositive property grows stronger. These elements mostly form ionic compounds.
• Alkali earth metals have importance as they possess strong electrical and thermal conductivities.

Alkali Metals

• Lithium, sodium, potassium, rubidium, caesium, and francium are the elements in Group 1 of the periodic table.
• They are known as alkali metals because they produce highly alkaline hydroxides when combined with water.
• With rising atomic numbers, alkali metals’ physical and chemical characteristics follow consistent patterns.
• Beyond the noble gas core, every alkali metal contains one valence electron.
• These elements include the highest electropositive metals due to the lightly bound s-electron in the outermost valence shell.
• They quickly lose electrons, resulting in monovalent M+ ions. As a result, they are never discovered in nature in a free state.
• Alkali metals are mainly silvery-white, tender, and lightweight metals.
• These elements exhibit a low density due to their vast size, which rises along with the group from lithium to caesium. Potassium, on the other hand, is lighter than sodium.
• Because the alkali metals have only one valence electron, their melting and boiling temperatures are low, suggesting weak metallic bonding.
• The alkali metals and their salts give an oxidising flame a distinct colour.

Alkaline Earth Metals Denser than Alkali Metals

Here are the reasons why alkaline Earth metals are denser than alkali metals:

• Alkaline earth metals exhibit a stronger metallic bond than alkali metals because they contain two electrons in their outermost shell. In contrast, alkali metals only have one electron in their valence shell. As a result, alkaline earth metals are denser than alkali metals.
• Because the radii of alkaline earth metals are less than those of alkali metals, the volume of the atoms is therefore smaller. This results in a higher density of alkaline earth metals.
• Because alkaline earth metals have a higher nuclear charge and a more significant number of valence electrons, metallic bonding is more powerful. As a result, they are denser than alkali metals.

Conclusion

Alkaline earth metals have smaller atomic and ionic radii than alkali metals. Since the radius of the atoms is lower, so is the volume of the atoms. Moreover, because of two valence electrons, atoms of alkaline earth metals have greater metallic bonding. As a result, alkaline earth metals are denser and more durable than alkali metals. From magnesium through radium, the density of alkaline earth metals usually rises, with calcium possessing the least density.