# CHAPTER SIX Electronic structure of atoms Orbitals and quantum

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CHAPTER SIX Electronic structure of atoms Orbitals and quantum

CHAPTER SIX Electronic structure of atoms Orbitals and quantum numbers The solution of Schrӧdinger equation for the hydrogen atom yields a set of wave functions and corresponding energies. Wave functions : orbitals describe the specific distribution of electron density. Each orbital has its own shape and characteristics. Bohr model introduced a single quantum number, n, to describe an orbit. The quantum mechanical model uses three quantum numbers, n, l, and ml to describe the orbit. Some important information about the quantum numbers, n, l, and ml. 1. The principal quantum number, n: has positive integer numbers ( 1,2,3, …) and 1 describes the orbital energy. E n (2.18 10 18 J ) 2 n Higher n means larger orbital, higher energy and therefore, less tightly bound to the nucleus. 2. The angular quantum number, l: has integral numbers from 0 to (n-1) for each value of n. l is described by the letters s, p, d, and f corresponding for the values to l of : 0, 1, 2, and 3. Value of l Letter used Word 0 s Sharp 1 P Principal 2 D diffuse 3 F fundamental 3. The magnetic quantum number, ml: has the values between (–l and +l) including zero. It describes the orientaion of the orbital in space. The following table summarizes the possible values of the quantum numbers (l and ml) for values of n. 1 PRESENTATIONS OF ORBITALS 2 The S orbitals, shape: Spherically symmetrical The P orbitals, shape: Dumbbell shaped The d orbitals, shape:Four-leaf clover 3 f-orbitals, shape: more complicated than d-orbitals. 4 MANY-ELECTRON ATOMS 5 See the text book to read the following : ELECTRON CONFIGURATION Hund′s Rule Condensed Electron Configuration Transition Metals The Lanthanides and Actinides ELECTRON CONFIGURATIONS AND PERIODIC TABLE 6 Solution a) b) [Xe] 4f14 6s2 6p3 c) there are three unpaired electrons. Home work 3 : Chapter 6: 3, 8, 10, 13, 15, 18, 25, 32, 36, 38, 39, 41, 51-55, 64-74 7