### Theory:

Four blocks of elements:
• We know that the electrons in an atom are arranged in shells around the nucleus.
• Each shell comprises one or more subshells in which the electrons are shared in a particular manner. These subshells are named s, p, d, and f.
• Based on the order of electrons in subshells, the periodic table elements are divided into four blocks: s, p, d and f.
s-Block Elements:
1. Alkali metals:
• It contains groups $$1$$ (alkali metals) and $$2$$ (alkaline earth metals) elements.
• They are also named as representative elements.
• Except for hydrogen, the elements in group $$1$$ are metals.
• When they react with water, they form solutions that turn red litmus paper in to blue.
• These solutions are classified as highly alkaline or basic. As a result, they are known as alkali metals.
2. Alkaline earth metals:
• The group $$2$$ elements are metals.
• They react with oxygen to form oxides, formerly known as 'earth,' and these oxides contain alkaline solutions when dissolved in water.
• As a result, these elements are known as alkaline earth metals.
p-Block Elements:
• These elements are found in periodic table groups ($$13$$-$$18$$).
• In addition to noble gases, they include the boron, carbon, nitrogen, oxygen, and fluorine families (except helium).
• They are also named as representative elements.
• The p-block is home to the widest variety of elements and is the only block that includes all three types of elements: metals, non-metals, and metalloids.
d-Block Elements:
• It contains elements from groups ($$3$$ to $$12$$).
• They are located in the middle of the periodic table.
• These block elements' properties are intermediate to that of s and p block elements. Hence, they are called transition elements.
f-Block Elements:
• It contains $$14$$ elements named Lanthanoides after (Lanthanum) La ($$57$$) and $$14$$ elements called Actinoides after (Actinium) Ac ($$89$$).
• They are fixed at the bottom of the periodic table.
• They are also named as inner transition elements.
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