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.
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PRESENTATIONS OF ORBITALS
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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.
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MANY-ELECTRON ATOMS
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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
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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
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