Answer: Electronic Configuration of first 20 elements is given below:
H – Hydrogen
He – Helium
Li – Lithium
Be – Beryllium
B – Boron
C – Carbon
N – Nitrogen
O – Oxygen
F – Fluorine
Ne – Neon
Na – Sodium
Mg – Magnesium
Al – Aluminium
Si – Silicon
P – Phosphorus
S – Sulphur
Cl – Chlorine
Ar – Argon
K – Potassium
Ca – Calcium
Explanation: s-Block Elements - S-block elements are those in which the last electron enters the s-orbital of the highest energy level.
Alkali metals and alkaline earth metals, Groups 1 and 2, respectively, make up the two groups that make up the s-block.
The phrase "p-block element" refers to an element whose last electron reaches the p-orbital of its outermost energy level.
The elements of the p-block are divided into Groups 13–18.
Metals, non-metals, and metalloids are all present in it.
Block Elements in d (Transition Elements)
D-block elements are those in which the last electron enters one of the five d-orbitals of the penultimate shell.
The d-block elements are found in Groups 3–12 in the middle of the periodic table.
Block Elements in f (Inner Transition Elements)
F-block elements are those in which the last electron enters one of the seven f-orbitals of the corresponding ante-penultimate shell.