Question

Which of the following statements is/are true for the long form of the periodic table?
(This question has multiple correct options)
A) It reflects the sequence of filling the electrons in the order of sub-energy levels s,p,d and f.
B) It helps to predict the stable valency states of the elements.
C) It reflects trends in physical and chemical properties of the elements.
D) It helps to predict the relative ionicity of the bond between any two elements.

Answer 1

According to the Aufbau principle, electrons first occupy the atomic orbitals having lowest energy levels. Once these atomic orbitals are filled, then electrons enter higher energy levels.

Complete step by step answer:
The following statements are true for the long form of the periodic table.
A) It reflects the sequence of filling the electrons in the order of sub-energy levels s,p,d and f
For this purpose, we can follow the Aufbau principle.
B) It helps to predict the stable valency states of the elements
For metals, the stable valency is equal to the group number. For nonmetals, the stable valence is equal to 8 minus the group number.
C) It reflects trends in physical and chemical properties of the elements
In a period, on moving from left to right, there is gradual variation in the physical and chemical properties. Similarly, in a period, on moving from top to bottom, there is gradual variation in the physical and chemical properties.
D) It helps to predict the relative ionicity of the bond between any two elements. During formation of a bond between highly electropositive alkali metal and highly electronegative halogen, then the bond will be mostly ionic. If formation of a bond is between less electropositive transition metal and less electronegative element such as phosphorus, then it has less ionic character.

Hence, all the four options (A), (B), (C) and (D) are correct answers.

Note: In the modern periodic table, elements are arranged according to the increasing order of atomic number. The physical and chemical properties of the elements are the periodic function of the atomic numbers.