Question

An element whose chemical properties are similar to chlorine is
A.Element with atomic number 2
B.Element with atomic number 7
C.Element with atomic number 19
D.Element with atomic number 35
E.Element with atomic number 74

Answer 1

To answer this question, you must recall the position of chlorine in the periodic table and its electronic configuration. Chlorine has atomic number 17 and is in the group 17 of the periodic table.

Complete step by step solution:
The electron configuration of an atom represents the arrangement of electrons distributed among the different shells and subshells of the atom. Mainly, electron configuration is used to represent the orbitals of an atom in its ground state but it can also depict the arrangement of electrons in a cation or anion.
Majority of the physical and chemical properties of an element can be related to its unique electronic configuration. The electrons in the outermost shell, known as the valence electrons, determine the chemistry of an element.
We know that, chlorine has 7 valence electrons, $2$ in its $3s$ orbital and $5$ in its $3p$ orbital
Of the given elements, the one which has the same number of valence shell electrons as chlorine would belong to the same group and would have similar chemical properties to chlorine.
Writing the electronic configurations for,
$(Z = 2):1{s^2}$ - 2 valence electrons
$\left( {Z = 7} \right):1{s^2}2{s^2}2{p^3}$ - 5 valence electrons
$\left( {Z = 19} \right):\left[ {Ar} \right]4{s^1}$ -1 valence electron
$\left( {Z = 35} \right):\left[ {Ar} \right]3{d^{10}}4{s^2}4{p^5}$ -7 valence electrons
$\left( {Z = 74} \right):\left[ {Xe} \right]4{f^{14}}5{d^5}6{s^2}$ -2 valence electrons
From the electronic configurations, we can see that an element with atomic number 35 has a similar outer shell configuration as that to chlorine and thus, must be having similar chemical properties as that of chlorine.

Hence, the correct option is D.

Note:
The periodic table can be used to derive relationships between various physical and chemical properties and behaviours of elements. The modern periodic table provides an essential framework that helps in the analysis of various chemical reactions, and is used widely in the fields of chemistry, nuclear physics and other sciences. It is based on the fact that atomic numbers dictate the physical and chemical properties of an element.