Modern periodic table - Practice Questions & MCQ

Modern Periodic Table (modified Mendeleev Periodic Table) :

1. It was proposed by Moseley.

2. The modern periodic table is based on the atomic number.

3. Moseley did an experiment in which he bombarded high-speed electron on different metal surfaces and obtained X-rays. 

He found out that 

where v = frequency of X-rays, Z = atomic number.

4. Modern periodic law : The physical & chemical properties of elements are the periodic function of their atomic number.

Characteristics of Modern Periodic Table

1. 18 vertical columns called groups.

2. IA to VIIA group, IB to VIIB, and zero group of inert gases.

3. Inert gases were introduced in the periodic table by Ramsay.

4. 7 horizontal series called periods.

Magic Number

The magic number of neutrons is the number of neutrons that are present in stable isotopes (non-radioactive). These magic numbers are: 2, 8, 20, 28, 50, 82, 126, and 184.

LONG FORM / PRESENT FORM OF MODERN PERIODIC TABLE :

(It is also called as 'Bohr, Bury & Rang, Werner Periodic Table)

1. It is based on the Bohr-Bury electronic configuration concept and atomic number.

2. This model is proposed by Rang & Werner

3. 7 periods and 18 vertical columns (groups)

4. According to I. U. P. A. C. 18 vertical columns are named as Ist to 18th group.

5. Elements belonging to the same group have the same number of electrons in the outermost shell so their properties are similar.

6. Elements belonging to the same group have same no. of electrons in the outermost shell so their properties are similar.

Important Points :

1. 2nd period elements (Li, Be, B) Shows diagonal relationship with 3rd period elements (Mg, Al, Si) so (Li, Be, B) are called Bridge elements. Because of same ionic potential value they shows similarity in properties. (Ionic potential = Charge/Radius)Li Be B Na Mg Al Si

2. 3rd period elements (Na, Mg, Al, Si, P, S, Cl) are called typical elements because they represent the properties of other element of their respective group.

3. Atomic number of last inert gas element is 86.
4.  
   • Number of Gaseous elements – 11 (H, N, O, F, Cl + Noble gases) 
   • Number of Liquid elements – 6 (Cs, Fr, Ga, Hg, Br, Uub)  
   • Bromine is the only non-metal which exists in liquid form. 
   • Number of Solid elements – 95 (if discovered elements are 112)
5. 2nd period contains maximum number of gaseous elements. They are 4 (N, O, F, Ne)