Question

What element in the fourth period of the periodic table has $ 5 $ valence electrons?

Answer 1

Hint: The periodic table, also mentioned as the periodic table of elements, is a tabular representation of the chemical elements organised by atomic number, electron arrangement, and repetitive chemical properties. The table's composition reveals certain periodic patterns.

Complete answer:
The elements in the periodic table's group $ 15 $ (column) $ VA $ all have $ {s^2}{p^3} $ electron configurations, making them have five valence electrons.
Nitrogen $ \left( N \right) $ , Phosphorus $ \left( P \right) $ , Arsenic $ \left( {As} \right) $ , Antimony $ \left( {Sb} \right) $ , and Bismuth $ \left( {Bi} \right) $ are among these elements.
When we take a look at the fourth energy level or period (row) of the periodic table, we can see that Arsenic is in group $ 17 $ and belongs to the fourth energy level.
The electron structure of arsenic is $ \left[ {Ar} \right]4{s^2}3{d^{10}}4{p^3} $
Arsenic's $ s $ and $ p $ orbitals each have two electrons, with a total of five valence electrons.
In general, the group number represents the number of valence electrons in a representative element.
Therefore, the element in the fourth period of the periodic table which has five valence electrons is Arsenic.

Note:
The atomic radius, ionisation energy, and electronegativity of elements in the same period appear to follow a pattern.
 $ 1) $ A chemical element's atomic radius is a measurement of the size of its atoms, typically the mean or normal distance between the nucleus's core and the border of the surrounding electron shells.
 $ 2) $ The minimal amount of energy needed to expel the most closely bound electron of an isolated neutral gaseous atom or molecule is known as ionisation energy.
 $ 3) $ An atom's ability to attract shared electrons (or electron density) to itself is known as electronegativity.