Justify the placement of O, S, Se, Te and Po in the same group of the periodic table in terms of electronic configuration, oxidation states and hydride formation.

Justify the inclusion of alkali metals in the same group of the periodic table with reference to the following. (i) Electronic configuration.

Explain the different oxidations states of S in terms of its electronic configuration.

Justify the inclusion of alkali metals in the same group of the periodic table with reference to the following. (iii) Oxides and hydroxides.

Justify the inclusion of alkali metals in the same group of the periodic table with reference to the following. (ii) Reducing nature.

Discuss the general characteristics of Group - 15 elements with reference to their electronic configuration, oxidation state, atomic size, ionization enthalpy and electronegativity.

Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative ? Why ?

The following are some statements about modern periodic table i) It is based on electronic configuration ii) It contains 7 periods and 18 groups iii) Each period begins with a non - metallic element

Numerous forms of the periodic table have been devised from time to time. A modern version which is most convenient and widely used is the long or extended from of periodic table. The aufbau principle and the electronic configuration of atoms provide a theoretical foundation for the periodic classification. The horizontal rows are called periods. There are altogether seven periods. The first period consists of 2 elements. The subsequent periods consists of 8, 8,18, 18 and 32 elements respectively. The seventh period is incomplete and like the sixth period would have maximum of 32 elements. Elements having similar outer electronic configurations in their atoms are grouped in vertical columns. These are referred to as groups or families. According to the recommendations of IUPAC, the groups are numbered 1 to 18 replacing the older notation of groups 0, IA, IIA, ....VIIA, VIII, IB.....VIIB. Each successive period in the periodic table is associated with the filling up next higher principal energy level following aufbau sequence. The number of elements in each period is twice the number of atomic orbitals available in the energy level that is being filled. All the elements are classified into four blocks, i.e., s-block, p-block, d-block, and f-block depending on the type of atomic orbitals that are being filled with electrons. What is the position of the element in the periodic table satisfying the electronic configuration (n-1)d^1 ns^2 for n=4 ?

Numerous forms of the periodic table have been devised from time to time. A modern version which is most convenient and widely used is the long or extended from of periodic table. The aufbau principle and the electronic configuration of atoms provide a theoretical foundation for the periodic classification. The horizontal rows are called periods. There are altogether seven periods. The first period consists of 2 elements. The subsequent periods consists of 8, 8,18, 18 and 32 elements respectively. The seventh period is incomplete and like the sixth period would have maximum of 32 elements. Elements having similar outer electronic configurations in their atoms are grouped in vertical columns. These are referred to as groups or families. According to the recommendations of IUPAC, the groups are numbered 1 to 18 replacing the older notation of groups 0, IA, IIA, ....VIIA, VIII, IB.....VIIB. Each successive period in the periodic table is associated with the filling up next higher principal energy level following aufbau sequence. The number of elements in each period is twice the number of atomic orbitals available in the energy level that is being filled. All the elements are classified into four blocks, i.e., s-block, p-block, d-block, and f-block depending on the type of atomic orbitals that are being filled with electrons. Elements A, B, C, D and E have the following electronic configuration: (A) 1s^2, 2s^2 2p^1 (B) 1s^2, 2s^2 2p^6 , 3s^2 3p^1 (C ) 1s^2, 2s^2 2p^6 , 3s^2 3p^3 (D) 1s^2 , 2s^2 2p^6 , 3s^2 3p^5 (E) 1s^2 , 2s^2 2p^6 , 3s^2 3p^6 Which among these will belong to same group in the periodic table ?