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Aufbau Principle and Shape of Orbital
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In this lesson we will learn about basic concept of filling of electrons for IIT-JEE students

Niranjay Kumar Dwivedi
(N.K.D.Sir) is a Complete Chemistry faculty for IIT~JEE, and NEET examination. with more then 8 year of Teaching experience

U
Unacademy user
Its very nice explanation mam,.thank you very much
  1. Aufbau Principle And Shape of Orbitals By-N.K.D. Sir Please -Rate review and share this lesson


  2. Aufbau Principle Aufbau is a German word meaning"building up". This gives us a sequence in which various sub-shells are filled up depending on the relative order of the energy of the subs-hells. The sub-shell with minimum energy is filled up first and when this obtains maximum quota of electrons, then the next sub-shell of higher energy starts filling 1S 2s (2p 3s 3p) (3d 4s) 4p 4d 4f 5s 5p 7s


  3. 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p Sub-shell ls Lowest value of n Lowest value of n Lowest value of rn 3d 5s 4d 0 Lowest value of n 6s Lowest value of n 5d 7s 5f 6d Lowest value of n


  4. Exceptions to Aufbau Principle: In some cases it is seen that actual electronic arrangement is slightly different from arrangement given by Aufbau principle. A simple reason behind this is that half-filled and full-filled sub-shell have got extra stability. Cr(24) Is2, 2s22p, 3s23p 3d1, 4s2 (wrong) (right) (right) Similarly the following elements have slightly different configurations than expected. Cu(29)s2s22p, 3s23p 3d9,4s2 (wrong) Mo Kr]4d 5s RuIKr] 4d 5s Rh Kr]4d85s AgKr] 4d05s Au Xe] 4f 5d06s


  5. Shapes of Atomic Orbitals S-orbital- An electron in considered to be immersed out in the form of a cloud. The shape of the cloud is the shape of the orbital. The cloud is not uniform but denser in the region where the probability of finding the electron in maximum. The orbital with the lowest energy is the s orbital. It is a sphere with its center of the nucleus of the atom. The s-orbital is said to spherically symmetrical about the nucleus, so that the electronic charge is not concentrated in any particular direction. 2s orbital is also spherically symmetrical about the nucleus, but it is larger than (i.e., away from) the ls orbit. 1S 2s nucleus adial node Node and Nodal Plane Node is defined as a region where the probability of finding an electron is zero. The planes passing through the angular nodal points are called nodal planes. Nodes No. of radial or spherical nodes n-1-1 No. of angular nodes Total no. of nodes n-1


  6. p-orbitals- There are three p-orbitals: Pk.Py and p. they are dumb-bell shaped, the two levels being separated by; a nodal plane, i.e., a plane where there is no likely hood of finding the electron. The p-orbitals have a marked direction character, depending as whether Px. p, and p, orbital is being considered. The p-orbitals consist of two lobes with the atomic nucleus lying between them. The axis of each p-orbital is perpendicular to the other two. The P Py and p, orbitals are equivalent except for their directional property. They have same energy; orbitals having the same energy are said to be degenerated Px Pz


  7. d-orbitals: There are five d-orbitals. The shapes of four d-orbitals resemble four leaf cloves. The fifth d-orbital loops different. the shapes of these orbitals are given below dyz dz