Question

What are the atomic numbers of elements whose outermost electrons are represented by: $ 3{{s}^{1}} $ and $ 3{{p}^{5}}. $

Answer 1

Hint : We know that all the elements are composed of a subatomic particle of electrons and protons. The atomic number is the total number of protons present in the element. Generally in neutral atoms, the number of electrons and protons is usually the same. According to the atomic number the elements are placed in the modern periodic table.

Complete Step By Step Answer:
In chemistry, a symbol is used as an abbreviation to describe an element. The atomic number or the proton number is displayed in the left subscript position of the element symbol to specify the element. This number defines the number of protons in the element. The modern version of the periodic table called the modern periodic table is the most conventionally and widely used. The horizontal rows are called periods and the vertical columns are called groups. The elements with a similar electronic configuration in the outer shell of the atoms are arranged in vertical columns called groups and families. The principal quantum number defines the main energy level of the shell, these shells can be further divided into subshells namely s, p, d, etc. The distribution of electrons in the last orbital reflects the position of the element in the periodic table. The period indicates the value of n for the outermost or valence shell. Here we have;
 $ 3{{s}^{1}}=1{{s}^{2}}2{{s}^{2}}2{{p}^{3}}. $ Thus by summing the values we get; $ 2+2+3=7. $
Therefore, the atomic number of the element is $ 7. $
 $ 3{{p}^{5}}=1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{2}}3{{p}^{5}}. $ Thus by summing the values we get; $ 2+2+6+2+5=17 $
Therefore, the atomic number of the element is $ 17. $

Note :
Remember that the first member of each of the groups of p-block elements differ in many respects from the other heavier members of the same group. This different behavior is due to the following reasons: The small size of the first element, also high electronegativity of the first element and the non-availability of d orbitals for bonding among the first row elements.