Group 2: Alkaline-earth metals

The elements that make up Group 2 (among 18 Groups) are considered as the alkaline rare earths in a generic sense. These are elements that are highly reactive and form ionic compounds. These elements form positive ions with a charge of two. This is due to the fact that the electrons in the outermost casing are located at a greater distance from the nuclei than those in the inner shell. They have a fixed oxidation state of two. Elements of group 2 are Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra) (Hanly & Zuberi-Khokhar, 1996).


1. Electronic configuration

General electronic configuration of Group 2 elements is 1s2 2s2 2p6 ns2. Elements of group 2 have following electronic configuration (Laing, 2007):
Be [4] 1s2 2s2 or [He] 4s²
Mg [12] 1s2 2s2 2p6 3s2 or [Ne] 4s²
Ca [20] 1s2 2s2 2p6 3s2 3p6 4s2 or [Ar] 4s²
Sr [38] 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 or [Kr] 5s2
Ba [56] 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 or [Xe] 6s2
Ra [88] 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 or [Rn] 7s2


2. Trend in the physical properties

The properties of the elements in Group 2 are similar to those of the elements in Group 1. The ionization energies of these elements are low. These substances carry electricity and heat very well. However, they are more reactive than group 1. Moreover, they are less metallic (Grochala, 2018).


2.1. Atomic and ionic radii

In group 2 atomic and ionic radius increases, so Be and Be2+ has smaller atomic and ionic radius while Ba and Ba2+ larger atomic and ionic radius (Hanly & Zuberi-Khokhar, 1996).

Atomic radius group 2 periodic table

Figure 1: Atomic radius of Group 2 elements

Ionic radius group 2 periodic table

Figure 2: Ionic radius of Group 2 elements

2.2. Ionization energy.

In group 2 Be has highest ionization energy as it is present at the top of its group while Ba has lowest ionization energy as it is present at the bottom of its group (Laing, 2007).

First ionization energy group 2 periodic table

Figure 3: First Ionization Energy of the Group 2 elements

2.3. Electropositive metallic character

Electropositive metallic character of group 2 elements increases down the group with exception of beryllium. Barium is more electropositive than magnesium (Grochala, 2018).


2.4. Melting and boiling point.

Group 2 elements, despite the exceptions of magnesium, have steadily decreasing melting points. So beryllium has highest melting point while barium has lowest melting point. While there is no gradual decrease in boiling point of group 2 elements (Hanly & Zuberi-Khokhar, 1996).

melting and boiling points group 2 periodic table

Figure 4: Melting and Boiling Points of the Group 2 elements

2.5. Flame coloration

In group 2, beryllium and magnesium do not impart any color to Bunsen flame because both these elements have very small size. It requires much energy for the excitation of the emission of radiations, so they are not excited by the energy of flame and do not impart any color to flame (Laing, 2007).

Flame color Group 2 periodic table of elements

Table: Flame color of  Group 2 elements

3. Chemical properties

Group 2 elements are more reactive as they have 2 electrons in their outer most shell. After losing these 2 electrons, they form dipositive ion. They reacts with different elements and form different compounds (Grochala, 2018).


3.1. Hydride

Elements of group 2 elements reacts with hydrogen and form corresponding hydrides. Beryllium do not react with hydrogen (Laing, 2007).

Group 2 elements reacts with hydrogen

Scheme 1: Group 2 elements reacts with hydrogen

Oxides from alkali earth metals

Scheme 2: Oxides from alkaline earth metals

3.2. Oxide and Hydroxide

Elements of group 2 reacts with oxygen and water and form corresponding oxide and hydroxides (Grochala, 2018).

Hydroxides from alkali earth metals

Scheme 3: Hydroxide from alkaline earth metals

3.3. Carbonate and bicarbonate

Important carbonate and bicarbonate of group 2 are:
Beryllium Carbonate (BeCO3) Magnesium Carbonate (MgCO3)
Calcium Carbonate (CaCO3) Strontium Carbonate (SrCO3) Barium Carbonate (BaCO3) Mg(HCO3)2, Ca(HCO3)2 etc.


4. Anomalous behavior of Beryllium

Beryllium is non-metallic. Beryllium are present in the mineral “Beryl”. The two metals occur together in “Beryl”. This occurrence is due to the diagonal relationship. Beryllium is the hardest. It has a high electronegativity and ionization enthalpyIt remains unaffected by boiling water or oxygen. The melting and boiling points are rather significant (Hanly & Zuberi-Khokhar, 1996).


4.1. Low atomic size

The most important anomalous properties of Beryllium are its low atomic size and its high charge to size ratio. This is because its valence shell contains no free d-orbitals. It also has a strong polarizing power. Beryllium has a p-orbital, which is not present in the other alkali metals. It also has a protected layer on its surface (Laing, 2007).


4.2. Precipitation

Beryllium’s ability to be precipitated from water is another one of its peculiar characteristics. It dissolves in caustic alkalis and liberates hydrogen gas. Beryllium hydroxide also dissolves in acid to form salts (Grochala, 2018).


4.3. Polarizing powers

Beryllium has similar polarizing powers. They also have similar ion sizes. They do not react easily with acids or atmospheric nitrogen. They’re also related to one another in a diagonal fashion. Beryllium chlorides has a chlorine ion bridged chloride structure. These polymeric structures are soluble in organic solvents. They are used as a catalyst in the Friedel-craft reaction (Hanly & Zuberi-Khokhar, 1996).


5. Uses of group 2 elements

Group 2 elements have many important uses. They are used in fireworks, consumer goods, and medicine. They can be used in electronics, semiconductors, and medical thermometers. They can also be used to produce fluorescent light and neon glass. These metals are used to produce cations with a charge of +1. These metals are used in inks, and paints. Some of them are also used in chemical production. Berylllium is processed to create high-strength vehicle parts like springs as well as shocks absorbers. It is also used in computers and aircraft parts (Laing, 2007; Grochala, 2018).



Generally speaking, Group 2 elements are the alkaline earth metals. These substances may be discovered in the crust of the planet, wherein they combine with water to form alkali mixtures. Some important properties of these metals include their alkali metal and alkaline earth metal forms, their negative reduction potentials, and their valence electron configurations.



1. Hanly, P. J., & Zuberi-Khokhar, N. (1996). Periodic limb movements during sleep in patients with congestive heart failure. Chest, 109(6), 1497-1502.
2. Laing, M. (2007). Where to put hydrogen in a periodic table? Foundations of Chemistry, 9(2), 127-137.
3. Grochala, W. (2018). On the position of helium and neon in the periodic table of elements. Foundations of Chemistry, 20(3), 191-207.