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Question: The element with atomic number \(Z = 115\) will be placed in: A. \({{\text{7}}^{{\text{th}}}}{\tex...

The element with atomic number Z=115Z = 115 will be placed in:
A. 7th period, I A group{{\text{7}}^{{\text{th}}}}{\text{ period, I A group}}
B. 8th period, IV A group{{\text{8}}^{{\text{th}}}}{\text{ period, IV A group}}
C. 7th period, V A group{{\text{7}}^{{\text{th}}}}{\text{ period, V A group}}
D. 6th period, V B group{{\text{6}}^{{\text{th}}}}{\text{ period, V B group}}

Explanation

Solution

The position of an element in periodic table of elements depends upon the electronic configuration of that element. From electronic configuration we can predict its period, group number and the block in which the element is present.

Complete step by step answer:
The periodic table of elements also known as simply periodic table is a tabular display of chemical elements. The basis of the arrangement of elements in tabular form is atomic number of elements. The elements are arranged in the tabular form to study the chemical properties. The electronic configuration of elements also plays an important role in the arrangement of elements in periodic tables.
Trick to predict the position of element in the periodic table:
Write down the electronic configuration of elements. The number of the maximum last shell in which the electron is filled is the period number of the element. The subshell of the atom in which the last electron exists is the block of the element. If the element is of s−blocks - block then it is either of group one or group two. If the element is present in p−blockp - block then the formula to find the group number is (12+number of electrons present in last p subshell12 + {\text{number of electrons present in last p subshell}}) and if the element is present in d−blockd - block then the formula to find group number is (2+number of electrons present in (n - 1)d subshell2 + {\text{number of electrons present in (n - 1)d subshell}}) where nn is the maximum number of shells present. The elements of f−blockf - block are arranged experimentally, their group number is 33 . If the atomic number of elements is above 100100 then we can find its group simply by subtracting 100100 from its atomic number and the group number of elements with the atomic number above 100100 is seven. So these concepts we will try to use in our problem.
We have given the atomic number 115115. The electronic configuration of this element is :
[Rn]5f146d107s27p3\left[ {{\text{Rn}}} \right]5{f^{14}}6{d^{10}}7{s^2}7{p^3}
The maximum number of the shell in electronic configuration is seven therefore the period number of element is also seven.
As we can see that it is p−blockp - block element, so the formula to find the group number is 12+number of electrons present in last p subshell12 + {\text{number of electrons present in last p subshell}} and the number of electrons in last p subshell{\text{p subshell}}is three so the group number is 15(12+3)15(12 + 3) or we can say V group{\text{V group}} .
The atomic number of the element is above 100 so we can use the other method also, we can subtract 100 from its atomic number and find out the group number.
⇒Group number = 115 - 100 = 15 or V A group\Rightarrow {\text{Group number = 115 - 100 = 15 or V A group}}
So the element belongs to 7th period, V A group{{\text{7}}^{{\text{th}}}}{\text{ period, V A group}}.

So, the correct answer is Option C .

Note:
The periodic table is very useful in understanding the chemical properties of elements. It can be used to compare the different trends for elements. The trends like electronegativity, ionization enthalpy, atomic size etc. can be easily predicted with the help of periodic tables.