Question

Which of the following statement(s) about the Modern periodic table is/are incorrect?
i.The elements in the Modern periodic table are arranged on the basis of their decreasing atomic number.
ii.The elements in the Modern periodic table are arranged on the basis of their increasing atomic number.
iii.Isotopes are placed in an adjoining group(s) in the periodic table.
A. i only
B. i and ii
C. ii and iii
D. i and iii

Answer 1

Hint: To find out the appropriate option which is incorrect regarding the modern periodic table, try to state about the features of modern periodic table and the number of blocks and how they are divided in the table. Each block has a definite number of orbitals where electrons are filled.

Complete step by step answer:
First of all, let us know about the modern periodic table. The modern periodic table of elements is the one that we use today. It is based on the concept of Mendeleev’s periodic table but is different t with respect to that; the elements are arranged in the increasing order of the atomic number and not atomic mass. The modern periodic table is broken down into four blocks i.e. the s-block, the p-block, the d-block and the f-block. So, s block has only one orbital and has two electrons spinning in opposite directions (spin up and spin down).
Likewise, the pblock has three orbitals and six columns and it can occupy a maximum of six electrons. The d-block has five orbitals and ten columns and can occupy a maximum of ten electrons while the f-block has seven orbitals and fourteen columns and can occupy a maximum of fourteen electrons. Thus, we can conclude that the number of columns equals the number of electrons which can be occupied in the subshell.
And, the azimuthal quantum number which is denoted by “l”, can be known by the block and with the help of this, we can determine the total number of energy subshells in a given energy level. As we see, option B is incorrect, stating that it has eight columns and eight electrons.
The statements (i) and (iii) about the Modern periodic table are incorrect.

The elements in the Modern periodic table are arranged on the basis of their increasing atomic number. Thus, \[N~\left( Z=7 \right)~\] is placed after \[C~\left( Z=6 \right).\]

Isotopes are placed in the same group in the periodic table. Thus, \[Cl-35~\] and \[Cl-37\] present in the same group (group $17$ ).

So, the correct answer is Option D.

Note: Moseley restated the Mendeleev’s periodic law as the physical and chemical properties of an element are a periodic function of its atomic number. This periodic law is also referred to as the Modern periodic law and was utilized to formulate the Modern periodic table. The azimuthal quantum number describes the shape of an orbital.