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 $\left[Ar\right]4s^{2}3d^{10}4p^3$
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.