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Modern periodic table was invented by Mendeleev which consists the lists of numerous elements in ascending order of atomic mass. Groups of elements with comparable physical and chemical characteristics are arranged in columns. Group 8 includes noble gases including Helium, Neon, Argon, Krypton, Xenon, & Radon, for instance. They are all stable, inert gases. The six elements that make up Group 2 are referred to as alkaline earth metals.
Periodic Table
The term “periodic table” refers to a tabular representation of chemical elements that are grouped in rows according to atomic number, with atoms that share anatomical structures and possess recurrent chemical properties appearing in vertical columns. The term “periodic table” refers to the table’s seven rows.
Group 2 Elements
Group 2 elements are known as alkaline metals because, when they interact with water, they produce alkaline solutions called hydroxides, and because the earth’s crust contains their oxides.
Alkaline earth metals are the elements that are found in group 2 of the periodic table. They are known as alkaline metals because, when combined with water, they produce an alkaline solution. Because their oxides do not heat up or dissolve in water, they are referred to as earth metals. Early scientists referred to any substance with these two characteristics as being “earth.” All group 2 element oxides are resistant to heat and insoluble in water. Alkaline earth metals are the classification given to the group 2 elements.
Density of Group 2 elements in g/cm3 are as follows:
Beryllium (Br) – 1.848 g/cm3
Magnesium (Mg) – 1.738 g/cm3
Calcium (Ca) – 1.55 g/cm3
Strontium (Sr) – 2.63 g/cm3
Barium (Ba) – 3.51 g/cm3
Radium (Ra) -5 g/cm3
Properties of the Group 2 Elements
Physical Properties
Atomic & Ionic Radii
Due to the charge as well as the addition of an electron to the same energy level, both ionic & atomic radius drop down the periodic table column, making them smaller as alkali metals & larger than that of other atoms of the same period. Both s-electron losses in alkaline earth metals might result in doubly positive cationic ions. A cationic atom has a smaller radius than a neutral atom. Ionic radii increase as you move further down the column.
Density
The volume of atoms is likewise less since the atoms’ radius is smaller. Additionally, because there are two valence electrons present, atoms have stronger metallic bonds. Alkali metals are less dense and less durable than alkaline earth metals. Magnesium and radium have the highest densities of all the alkaline earth metals, with the calcium having the lowest.
Melting Points and Boiling Point
Due to their smaller size and solid metallic bonding in a compact structure, alkaline earth metals have greater melting temperature and boiling temperature than alkali metals. The melting and boiling points of the alkaline earth metals, with the exception of magnesium, decrease from Beryllium to Barium.
Ionization Energy
To create an octet noble gas configuration, alkaline earth elements can share both of their valence electrons. As a result, they have two ionisation energies:
The energy needed to take the first electron out of a neutral atom is known as the 1st ionisation energy of the alkaline earth metals. Due to smaller radii, the electrons being held more securely by the higher nuclear charge, and also electrons being removed from a fully filled and hence stable subshell, it is larger than that of the alkali metal atom.
Alkaline earth metals’ second ionisation energy will be higher than that of the atom’s initial ionisation energy but lower than that of any alkali metal in order to ionise the 2nd electron from the cation. The atom adopts a noble gas configuration, allowing both electrons to be removed despite the higher ionisation ionisation energy. The smaller size & higher charge also assist in overcoming the higher ionisation energy by producing additional lattice energy as a result of the close packing of ions or atoms in solids. Liquids also have higher hydration energy due to the larger solvation.
Chemical Properties
Reaction with water
Beryllium doesn’t interact with water, not even at higher temperatures. Magnesium only reacts with hot water to produce hydroxides and hydrogen. Magnesium gets a protective layer of its oxide, shielding it from additional water molecule attack. When other alkaline earth metals interact with even ice-cold water, hydrogen is produced.
M + 2H2O → M(OH)2 + H2↑
Hydrides
Hydrogen and beryllium do not react right away. Beryllium hydride is produced when beryllium chloride and lithium aluminium hydride are combined. Covalent hydrides, that have 2 metal atoms bonded to each hydrogen, are created by beryllium and magnesium. A molecule having 3 centres sharing merely two electrons is called a banana bond.
M + H2 → MH2
Conclusion
The s-block of periodic table contains the Group 2 elements.
The group 2 elements are known as alkaline earth metals because they can produce alkaline oxides and hydroxides, which are found in the crust of the earth.
The first period contains hydrogen, the second period beryllium, the third period magnesium, the fourth period calcium, the fifth period strontium, the sixth period barium, and the seventh period radium. Beryllium (Z = 4), Magnesium (Z = 12), Calcium (Z = 20), Strontium (Z = 38), Barium (Z = 56), and Radium (Z = 88) make up Group 2.
