Quantum Atom. Problem Bohr model of the atom only successfully predicted the behavior of hydrogen...
Transcript of Quantum Atom. Problem Bohr model of the atom only successfully predicted the behavior of hydrogen...
Quantum Atom
Problem
Bohr model of the atom only successfully predicted the behavior of hydrogen
Good start, but needed refinement
Heisenberg Uncertainty Principle
It is not possible to know both the position and momentum (mv) of an electron
Cannot assume that the electron is moving around the nucleus in a well-defined orbit as in the Bohr model
Louis de BroglieSuggested matter that is assumed to be of a particle nature, does have wavelike properties
Developed an equation for actually calculating this wavelength of matter
For very small particles, wavelength is significant
h
mv
Wave Function
Erwin Schrodinger developed a series of equations that describe the areas of probability of finding an electron
There are different values of these wave functions that occur at different energy levels
Wave function are called Orbitals
Quantum Mechanics
Describes mathematically the properties of an electronShows regions of probability of finding an electron
Quantum Numbers
Principal Quantum Number (n) – same as the Bohr energy levelAlso called shellsRange from n=1 to n=7
Subshell or Sublevel
Angular Momentum Number
Come in four typess subshell (spherical)p subshell (dumbbell)d subshell (four lobes) f subshell
Orbital
Magnetic Quantum Number These are the orbitals (hold 2 e- each)Each sublevel may have more that one
orbital with a different orientation in spaces ( 1 orbital) p ( 3 orbitals) d (5 orbitals) f (7 orbitals)
Main Level Sublevels Number of orbitals
Electrons in sublevels
Total Electrons in Main Level
1 s 1 2 2
2 sp
13
26
8
3 spd
135
26
1018
4 spdf
1357
26
1014
32
Degenerate Orbitals
Orbitals that have the same energies
Electron Spin Number
Electron behaves as if it is spinning on its axis
Fourth Quantum number is the spin number
Spinning electrons produce magnetic fields
Pauli Exclusion Principle
No two electrons can have the same set of four quantum numbers
If an orbital has two electrons in it, they must have different spins
Electrons in the same orbital with different spins are called paired electrons
Configuration
Arrangement of electrons in the atom
Aufbau Principle – orbitals fill in order of increasing energy
Orbital Diagram of Li ( 3 e-)
1s22s1
Orbital Diagram of B (5 e-)
1s22s22p1
Hund’s Rule
Electrons occupy degenerate orbitals singly first
Orbital Diagram of C (6 e-)
1s22s22p2
Orbital Diagram of Ne (10 e-)
Configuration 1s22s22p6
Example
Determine the configuration of
Fe
Br
Magnetism
When electrons in half-filled degenerate orbitals spin in the same direction, the material is magnetic
Valence Electrons
Outer shell electrons
Ones in the last main energy level
▪ K 1s22s22p63s23p64s1 1 valence e
• Fe 1s22s22p63s23p64s23d6 2 valence e