How Many Elements are There in s-Block

Introduction

Alkali metals, also known as group one elements, are s-block elements with just one electron in their s-orbital, whereas alkaline earth metals, also known as group two elements, are s-block elements with two electrons in their s-orbital. The electrons in an atom occupy several sub-orbitals of the available energy levels in ascending order of energy. The last electron of an atom can be located in the s, p, d, or f-subshells. So called s-block elements are those that have the last valence electron in the s-suborbital of the atom. The Periodic Table's s-block elements are those in which the final electron enters the most outer s-orbital. The s-block of the Periodic Table is made up of two groups (1 & 2) since the s-orbital can only hold two electrons.

The elements lithium, sodium, potassium, rubidium, caesium, and francium make up Group 1 of the Periodic Table. The alkali metals are the name given to them altogether.

These are so named because when they react with water, they produce hydroxides that have a very alkaline character.

Beryllium, magnesium, calcium, strontium, barium, and radium are among the elements in Group 2. With the exception of beryllium, these substances are collectively referred to as "alkaline earth metals". These have this name because their metal oxides and hydroxides are naturally alkaline.

Properties of s-Block Elements

The properties of both alkali and alkaline earth elements exhibit a regular gradation within each group of elements. However, the first s-block members, Lithium and Beryllium, differ significantly from the rest of their members while also resembling the diagonal element in the following column.

These s-block elements' anomaly is caused by;

• Very small atomic and ionic sizes.

• Higher charge density (charge/atom volume).

• Heightened polarisation.

• There are no d-orbitals.

With increasing polarisation, the first s-block element becomes more covalent, distinguishing it from the other ionic s-block members.

Due to their similarity in size and charge density to the element diagonally positioned in the following group, they are similar to it (diagonal relationship).

It is observed that the physical and chemical properties of these s-block elements change in a particular pattern as the atomic number of the elements increases. The group's various properties have undergone the following modifications:

Chemical Properties Of s-Block Elements

Atomic and Ionic Radii

When the s-block elements of the contemporary periodic table are examined during that particular time, the alkali metals are larger than other elements. The atomic number increases together with the total amount of electrons and the number of freshly formed shells. As you go along, the atomic number moves down the group.

Ionisation Enthalpy

There is less attraction between the nucleus and the electrons in the outermost shell as we proceed down the group because the size of the atoms increases. As a result, the ionisation enthalpy drops. Compared to other elements, alkali metals have a relatively lower ionisation enthalpy.

Hydration Enthalpy

The hydration enthalpy reduces as the ionic sizes of the elements grow. The high charge/radius ratio of the atom allows it to store more water molecules around it, therefore as the size of the ion shrinks, the hydration enthalpy rises. As a result, the ion becomes hydrated.

Physical Properties of s-Block element

• Down the group in the s-block elements, the density of the alkali metals rises. The density of potassium is different from that of sodium, for example.

• Due to the brittle metallic bonding, alkali metals have a low melting and boiling points.

• Due to the heat produced by the flame, which excites the valence electrons from one energy level to another energy level, alkali metals and their corresponding salts have the ability to add colour to the oxidising flame. This aids in the flame test's ability to find alkali metals.

Diagonal Relationship Within s-Block Elements

There is a diagonal relationship between adjacent elements that are located in the second and third periods of the periodic table in s-block elements. For example, the properties of lithium, which are found in group 1A and the second period, are similar to those of magnesium, which is found in the second group and third period. The characteristics of beryllium in the second group and second period and those of aluminium in the third group and third period share a number of similarities. If the two objects' qualities are similar, they are referred to as diagonal pairs or diagonal neighbours.

The properties of the s-block elements are very different from those of the other elements in the subgroup to which they belong. Moving from left to right and down the group reveals this relationship; the periodic table has opposing elements. For instance, as we move across the period and move down the group, the electronegativity of the s-block elements rises. As a result, when it is moved diagonally, the opposing tendencies cancel out, almost maintaining the same electronegativity value.

There is a diagonal relationship between adjacent elements that are located in the second and third periods of the periodic table in s-block elements. For example, the properties of lithium, which are found in group 1A and the second period, are similar to those of magnesium, which is found in the second group and third period. The characteristics of beryllium in the second group and second period and those of aluminium in the third group and third period share a number of similarities. If the two objects' qualities are similar, they are referred to as diagonal pairs or diagonal neighbours.

Similarities Between Lithium and Magnesium

• Lithium and magnesium both have harder surfaces than the other elements in their respective families.

• Lithium and magnesium chlorides have the capacity to dissolve in ethanol.

• Compared to other elements in their groupings, they are lighter.

• Water and magnesium have a mild reaction. Less soluble are the oxides and hydroxides.

• Lithium and magnesium do not produce superoxides when they interact with too much oxygen.

• When the carbonates of magnesium and lithium are heated, carbon dioxide and its corresponding oxides are produced.

The first elements of Groups 1 and 2, respectively, lithium and beryllium, display

a few characteristics that are distinct from those of the other group members.

They are similar to the second member of the group below in terms of these unusual traits.

Lithium therefore like magnesium, and beryllium resembles aluminium in many of its characteristics. In the periodic table, this kind of diagonal resemblance is frequently referred to as a diagonal connection. The similarity in ionic sizes and/or charge/radius ratios of the elements is what causes the diagonal relationship.

In high concentrations, biological fluids contain monovalent sodium and potassium ions as well as divalent magnesium and calcium ions.

These ions carry out crucial biological processes like nerve impulse and ion balance maintenance.

Similarities Between Beryllium and Aluminum

• With too much alkali, the hydroxides of aluminium and beryllium combine to form the corresponding ions.

• Due to the presence of an oxide film on the metal's surface, both of these elements can resist an acid attack.

• Both of these metals are prone to forming complexes.

• Both of these metals' chlorides have the ability to dissolve in organic solvents.

Conclusion

The [noble gas]ns1 electronic configuration is the default for s-block elements and [noble gas] ns2 for alkali metals and alkaline earth metals, respectively. Barium and strontium are substantially less common. Radium is the rarest element of all, making up only 10–10% of igneous rocks. Beryllium is also rare.