1. Electrons  Energy levels – region around nucleus where electrons are likely to be found.  Fixed energy levels are like rungs of a ladder. An electron must be on a rung not in between.

2.  To move from one energy level to the next, electrons must gain or lose energy.  A quantum is the amount of energy it takes to move up an energy level.  When an electron jumps from one energy level to another it is called a “quantum leap.”  Energy is given off if an electron moves to a lower one.  The lowest allowable energy level of an atom is called the ground state.  When an atom gains energy it is said to be excited. Electrons

4. Modern Model of the Atom  Quantum Mechanical Model  Schrodinger Equation--mathematical equation that describes the behavior of electrons as waves instead of particles.  Deals with probabilities there is not an exact path of an electron.

5. Atomic Orbitals  An electron can be placed in an orbital based on the 4 quantum numbers  Principle Quantum Number (n)—primary energy levels  Second Quantum Number (l) —energy sublevel  Third Quantum Number (m) —which orbital  Fourth Quantum Number (s) —the electron spin

6. Atomic Orbitals  Principle energy level (n)  There are 7 principle energy levels that correspond with the 7 periods of the periodic table  Max number of electrons in each level = 2n 2.  n = 1: 2(1) 2 = 2 electron max  n = 2: 2(2) 2 = 8 electron max  n = 3: 2(3) 2 = 18 electron max  n = 4: 2(4) 2 = 32 electron max

7. Atomic Orbitals  Second Quantum Number (l)  Within energy levels there are sublevels  n tells the principle energy level and the number of sub levels in that level. PQN (n) # sublevels Type (l) n= 1 1s n = 2 2 s, p n = 3 3 s, p, d n = 4 to 7 4 s, p, d and f

8. Atomic Orbitals  The max number of electrons that any orbital can hold is 2. Sublevel (l)Orbital's (m)Total electrons shape s12sphere p36Dumb bell d5104 leaf clover f714complex g918complex

10. 3 Rules to Electron Configurations  Aufbau Principle – electrons enter orbitals of lowest energy first.  “Lazy Tenant Rule”

11.  Hund’s Rule – when electrons occupy orbitals of equal energy, one electron enters each orbital until all the orbitals contain 1 electron with parallel spins. 3 Rules to Electron Configurations WRONG RIGHT

12.  Pauli Exclusion Principle – an atomic orbital can have a max of 2 electrons with opposite spin. 3 Rules to Electron Configurations

14.  Orbital Diagram for Oxygen with 8e - Orbital Diagram Notation 1s 2s 2p Examples:Examples: AluminumAluminum KryptonKrypton

15. Electron Configurations  The way in which electrons are arranged around the nuclei.

16. S 16e - 1s 2 2s 2 2p 6 3s 2 3p 4  Longhand Configuration Electron Configuration Notation  Noble Gas Configuration  For larger elements, you can short hand the lower elements electron configuration by simply using the noble gas immediately previous to the element. S16e - [Ne] 3s 2 3p 4

17. s-block1st Period 1s 1 1st column of s-block Electron Configuration Example  Example - Hydrogen

18. © 1998 by Harcourt Brace & Company s p d (n-1) f (n-2) 12345671234567 6767 Using Periodic Table for Electron Configurations

19.  Examples:  Oxygen  Potassium  Nickel  Lead  Fluorine -1 (gained 1 e - ) Electron Configuration Notation Longhand

20. [Ar]4s 2 3d 10 4p 2 Electron Configuration Example  Example - Germanium

21.  Examples:  Oxygen  Potassium  Nickel  Lead  Calcium +2 (lost 2 e - ) Noble Gas Electron Configuration Example

22. C. Johannesson Copper EXPECT :[Ar] 4s 2 3d 9 ACTUALLY :[Ar] 4s 1 3d 10 Copper gains stability with a full d-sublevel. Electron Configuration Exceptions Examples

23. C. Johannesson Chromium EXPECT :[Ar] 4s 2 3d 4 ACTUALLY :[Ar] 4s 1 3d 5 Chromium gains stability with a half-full d-sublevel. Electron Configuration Exceptions Examples