Table of Contents
Introduction to Group 2 Elements
Group 2 in the periodic table houses some of the most important elements that play crucial roles in our day-to-day lives. Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium are the elements in Group 2. (Ra). Because they have two electrons in their outermost S orbital, Group 2 elements have comparable chemical and physical characteristics. As a result, they are also called s block elements.
Be - 1s2 2s2
Mg – 1s2 2s2 2p6 3s2
Ca – 1s2 2s2 2p6 3s2 3p6 4s2
Sr - 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2
Ba - 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2
Group 2 elements, usually known as alkaline earth metals, occupy the second column of the periodic table and have the typical electrical configuration ns2. Under normal circumstances, all alkaline earth metals appear as silvery-white solids. Because alkaline earth metals quickly shed electrons from their totally filled s orbitals to +2 charge cations, +2 is their most common oxidation state. They establish a strong metallic connection due to the presence of two valence electrons. As a result, alkaline earth metals are denser and harder than alkali metals.
Group 2 elements’ characteristics are as follows:
The atomic radius of group 2 elements grows down the periodic table, as does the size of the atoms. As a result, the effective nuclear charge of electrons falls throughout the periodic table, and the outermost electrons are less constrained by the nucleus.
The ionic radius of group 2 elements is less than the atomic radius. When an atom loses one of its electron shells, the remaining electrons are closely held by the nucleus.
Energy of ionization - Group 2 elements may provide both two valence electrons to produce the Noble gas configuration, also known as the octet configuration. As a result, they have two ionization energies.
The first ionization energy required to remove a loosely bound electron from a neutral atom in group 2 elements is more than that required for alkali metal atoms.
Reasons include: because of the smaller radii, the larger nuclear charge firmly holds the electron, and electrons are withdrawn from a completely filled subshell, resulting in the formation of a stable subshell.
The second ionization energy of group 2 elements is the energy required to remove the cation's second electron. So, the second ionization energy is greater than the first ionization energy but less than the second ionization energy of alkali metals. The reasons are: the atom transforms into a noble gas configuration, and greater lattice energy.
Melting and boiling points: As the melting point of group 2 elements drops, so does their boiling point. Metallic bonding degrades as atomic size grows. Alkaline earth metals have greater melting and boiling points than alkali metals due to their smaller size and closed-packed structure, i.e., strong metallic bonding.On heating, all alkaline earth metals except Beryllium (Be) and Magnesium (Mg) exhibit distinctive color. Because the movement of free electrons in their salt is present in their metal ions. This distinguishing color is apparent in the spectrum and can be used to identify them. Calcium has a brick red color, Strontium has a crimson red color, and Barium has an apple green color.
Chemical Properties Of Group 2 Elements
Reaction with Water
Hydroxides M(OH)2 and hydrogen gas are formed when group 2 elements combine with water (H2). Beryllium (Be), on the other hand, does not react with water.
For example:
Ca(s) + H2O(l) → Ca (OH)2(aq) + H2(g)
Ba(s)+2H2O(l)→ Ba (OH)2(aq)+H2(g)
Oxidation Reaction
Beryllium (Be) does not react with O2, although other alkaline metals do, forming metal oxide.
For example:
Ca(s) + O2(g) → 2CaO(s)
Sr(s)+O2(g)→SrO2(s)
Reaction with Hydrogen
Beryllium does not directly react with hydrogen; nevertheless, Beryllium hydride may be made by reducing beryllium chloride with lithium aluminum hydride.
For example:
2BeCl2 + LiAlH4 → 2BeH2 + LiCl + AlCl3
All of the elements in Group 2 react with H2 to generate metallic hydrides.
For example:
Ca(s)+H2(g)→CaH2(s)
Reaction with Halogens
Metal halide is formed when group 2 elements react with halogen. The halogen reactivity decreases from fluorine (F) to iodine (I).
For example:
Mg(s)+Cl2(g)→MgCl2(s)
Beryllium combines with halogen to generate beryllium halides, which are naturally covalent due to their high charge (Be+2) and tiny size. Beryllium Fluoride is an ionic chemical, whereas BeCl2, BeBr2, and BeI2 are extremely covalent.
Read more about Chemical Periodicity
Beryllium's Unusual Behaviour
The first element of Group 2 Beryllium exhibits unusual behavior when compared to the other members of the group.
- It has an extremely high melting and boiling point.
- It has no reaction with water.
- When compared to other members of the group, it has extremely tiny atomic and ionic sizes.
- Among the alkaline earth metals, beryllium is the hardest.
- It just has four coordination numbers.
- Beryllium does not generate hydride when it reacts directly with hydrogen.
Diagonal Relationship Between Beryllium And Aluminum
Beryllium and aluminum have a diametric connection. Because beryllium and aluminum have almost identical ionic radius and charge / radius ratios, they exhibit certain comparable properties. Some of their parallels are listed below.
- Be and Al ions have a high proclivity to form complexes.
- They do not react with the oxygen and nitrogen in the atmosphere.
- Even at high temperatures, Be and Al do not react with water.
- Both produce polyvalent bridging hydrides, which are covalent in character.
Uses Of Group 2 Elements
Calcium oxide and quick lime (Cao): Cao is a white amorphous material that may be produced by heating limestone in a rotating kiln at temperatures ranging from 1070 to 1270 degrees Celsius.
CaCO3 → CaO + CO2
Uses:
It is a fundamental ingredient in the production of cement.
It is also employed in sugar refining and the production of different dyes.
Plaster of Paris [Calcium hemihydrate, CaSO4.1/2H2O]: It may be made by heating gypsum, CaSO4.2H2O, to 393 K.
Uses:
It's used in dentistry and as a decorative material.
It is widely used in the construction sector and as a plaster.
When a bone fracture or sprain occurs, it is utilized to immobilize the damaged organ portion.