S-block elements

The s-block is on the far left side of the periodic table and contains all of the elements found in the first two columns (columns 1 and 2) and helium, located in the upper right corner of column 8A (column 18 on some versions of the periodic table). 

Periodic table S-block

The 14 elements contained within these columns are the s-block elements. Their valence electrons (outermost electrons) are in an s-orbital that connects all s-block elements. 

The s orbital is spherical and can accommodate up to two electrons. Column 1 elements have one electron in the s-orbital, while column 2 elements (plus helium) have two electrons in the s-orbital.

Hydrogen (H), helium (He), lithium (Li), beryllium (Be), sodium (Na), magnesium (Mg), potassium (K), calcium (Ca), rubidium (Rb), strontium (Sr), cesium (Cs), barium (Ba), francium (Fr), and radium (Ra) are all s-block elements . 

This electronic configuration-based block nomenclature roughly corresponds to elements based on chemical properties. The s and p-blocks are the main group elements. In contrast, the d-block corresponds to transition metals, and the f-block contains nearly all lanthanides (including lanthanum) and actinides (like actinium). 

There are some uncertainties in groupings. For example, zinc, cadmium, and mercury are frequently regarded as main group elements rather than transition group elements because they are chemically and physically more similar to the p-block elements than the other d-block elements. 

Group 3 elements are sometimes referred to as main group elements due to their resemblance to s-block elements. The f-block contains no numbered groups (between groups 2 and 3). 

Properties of s-block elements

If the elements were houses in our fictitious s-block neighbourhood, they would be nearly identical, with only minor variations. This is distinct from the other periodic table neighbourhoods, with a broader range of houses in various shapes, sizes, and colours.

The s-block elements are all metals. They have a gleaming, silvery appearance, are good conductors of heat and electricity and their valence electrons are easily lost. Indeed, the s-block elements lose their s-orbital valence electrons so quickly that they are among the most reactive elements on the periodic table. 

Except for hydrogen, column 1 elements, also known as alkali metals, permanently lose one valence electron to form a +1 ion. As a result, these metals have a silvery appearance, are very soft, have a low melting point, and have low density. 

These metals react violently with water, releasing energy and flammable hydrogen gas. Therefore, they are kept in mineral oil to avoid an unfavourable reaction or, worse, an unfavourable explosion. 

Na (s) + H2O (l) → NaOH (aq) + H2 (g)

To form a +2 ion, column 2 elements (except helium) permanently lose two valence electrons. Alkaline earth metals, like alkali metals, are silvery, shiny, and relatively soft. Because some of the elements in this column have violent reactions to water, they must be stored with extreme caution.

s-block elements are commonly used in fireworks. The ionic forms of potassium, strontium, and barium appear as brilliant purples, reds, and greens in fireworks displays.

Francium is thought to be the rarest naturally occurring element on the planet. Only one atom of francium is believed to exist on Earth at any given time. The nucleus of francium is highly unstable and decays rapidly. Therefore, it ceases to exist the moment it is created.

Here is a congregation of various properties of s-block elements :

• When the s-block elements of the modern periodic table are examined, it is discovered that the size of the alkali metals is greater than that of other elements in a given period. The total number of electrons increases with the addition of shells as the atomic number increases.
• As we move down the group, the size of the atoms decreases, reducing the attraction between the nucleus and the electrons in the outermost shell. As a result, the enthalpy of ionisation decreases. The ionisation enthalpy of alkali metals is lower than that of other elements.
• The hydration enthalpy decreases as the ionic sizes of the elements increase. Because of the high charge/radius ratio, the atom can accommodate a more significant number of water molecules around it and becomes hydrated as the ion’s size decreases.

In s-block elements, a diagonal relationship exists between adjacent elements in the second and third periods of the periodic table. The properties of lithium in group 1A and the second period, for example, are similar to the properties of magnesium in the second and third periods.

Similarly, the properties of beryllium in the second group and second period are similar to the properties of aluminium in the third period and third group. A diagonal pair, also known as diagonal neighbours, is a pair of elements with similar properties.

The properties of s-block elements differ significantly from those of the other elements in the sub-group to which they belong. However, the diagonal neighbours have a lot in common. Such relationships are noticed increasingly as one moves from left to right and down the periodic table; the periodic table contains opposing factors.

Conclusion

The s-block elements belong to the modern periodic table’s Groups 1 and 2. s-block elements are classified into two types: those with one electron (s1) and those with two electrons (s2) in their s-subshell. For example, alkali metals have one electron in their s-orbital and are s-block elements, whereas alkaline earth metals have two electrons in their s-orbital. 

Except for helium, all s-elements are chemically very reactive. Due to their high electropositivity, s-block metals frequently form ionic compounds with nonmetals, particularly the highly electronegative halogen nonmetals.