The S-Block Elements

The s-block elements of the periodic table belong to groups 1 and 2 of the periodic table. Group 1 elements are called alkali metals, and group 2 elements are called alkaline earth metals. Oxides and hydroxides are named for their basicity. Alkali metals have one electron in the valence shell of their atoms, while alkaline earth metals have two electrons. These metals are highly reactive and can generate monocations and dications. The members of the s-block elements of the periodic table are on the far left of the periodic table. The s-block elements are also called active metals. This article will discuss all the s-block elements of the periodic table, which are placed in groups comprehensively.

What are s-block elements?

There are four possible subshells in an atom: s (sharp), p (principal), d (diffuse) and f (fundamental). On looking closely, we will see that all elements in the periodic table can be divided according to the subshell to which the last electron was added.

Hence, the classification of block elements into s, p, d, f.

s-block elements are elements in which the last electron has been added to the s subshell. Groups I and II belong to block s on the far left and contain the most electropositive elements on the periodic table.

Examples of s-block elements of the periodic table

Hydrogen, lithium, helium, sodium, beryllium, potassium, calcium, cesium, strontium, francium, magnesium, rubidium, barium and radium.

Physical and chemical properties of s-block elements

The modern periodic table results from various table designs developed by scientists over the centuries. This format is based on Mendeleev’s Periodic Table of Elements, which originated in 1869. Since then, the world of chemistry has changed dramatically. We better understand the behaviour of elements. In this section, we will study the s-block elements found in groups IA and IIA of the modern periodic table. 

Characteristics of the s-block of the periodic table of elements

The outermost orbital of an s-block element is a spherical s orbital. Since the s orbital can hold up to 2 electrons, each element has 1 or 2 electrons. It is possible to lose these easily by losing one electron in the outermost orbital to form a single positive ion or by losing two electrons to form a double positive ion.

They have low ionisation potential and low electronegativity. They are good conductors of heat and electricity, except for H2 and He. They are silvery, shiny metallic substances (except for the gaseous nonmetals hydrogen and helium). They are malleable and ductile, i.e., they can be processed into plates and wires (exceptions: H2, He).

They readily form ionic salts with most nonmetals. Aqueous solutions of their oxides are alkaline. They are listed in the two left columns of the periodic table, except He, which is on the right. The elements in the first column are called alkali metals, and the elements in the second column are called alkaline earth metals. The elements of the block are – 

Column 1: H, Li, Na, K, Rb, Cs, Fr.

Column 2: Be, Mg, Ca, Sr, Ba, Ra.

Periodic trends in the s-block elements

Periodic trends are specific patterns in the properties of chemical elements displayed in the periodic table. Significant periodic trends include electronegativity, ionisation energy, electron affinity, atomic radius, ionic radius, metallic properties and chemical reactivity.

Alkali metals are silvery-white, have a low melting point, and are soft and highly reactive.

The ion size and the atomic size increase towards the bottom of the group; on the other hand, the ionisation enthalpy decreases towards the bottom of the group. These compounds are mainly ionic. Hydroxides and oxides dissolve in water to form strong bases; some sodium compounds are sodium chloride, sodium bicarbonate, etc. Sodium hydroxide is produced using the Kastner-Kellner process, and sodium carbonate is produced using the Solvay process with reduced atomic size.

Alkaline earth metals- hydroxides and oxides are less basic. Some calcium compounds are calcium carbonate, calcium hydroxide and the like. Group 2 elements are less reactive as compared to group 1 elements. The alkaline earth metals are highly metallic and good conductors of electricity. Chemically they are all strong reducing agents.

Conclusion

This article examines alkali and alkaline earth metals and why they are called s-block elements. We studied the unusual behaviour of the first member of the group. We now know the physical and chemical properties of alkali and alkaline earth metals and their applications.

Alkali and alkaline earth elements exhibit a regular gradient between their respective group elements, which are more like the diagonal elements present in the next column. The chemical properties of alkaline earth metals are very similar to those of alkali metals; however, there are some differences also due to the decreasing and increasing atomic, ionic size and increased cationic charge of alkaline earth metals.