[" In the sixth period,the orbitals being "],[" filled are "]

In the sixth period , the orbitals that are filled are :

In the sixth period , the orbitals that are filled are :

In the 5^th period the orbitals being filled are

In the sixth period, the orbitals being filled with electrons are

a. In the sixth period, after filling of 6p orbitals, the next electron (i.e. 57th ) enters the 5d -orbital against aufbau principal and there after the filling of seven 4f -orbitals starts with cerium (Z = 71) . Explain this anomalous behaviour.

which quantum numbers represent the orbitals being filled in the ground state for the elements Sc (21) to Zn (30)?

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 ?

While filling up of electrons in the atomic orbitals, the 4s-orbital is filled before the 3d-orbital. Explain why.