ChemCatalyst What are the three subatomic particles and their corresponding properties? Do you think similar properties of the elements are related to subatomic particles? If yes, which one? If no, why not?

The Quantum Mechanical Model & Electron Configuration

Part 1 Models of the Atom

Bohr Model (old/ bio version) Electrons move around the nucleus in fixed spherical orbits with fixed energies Orbit: energy level designated by an integer Electrons can go to a higher or lower energy level Need to gain or lose a quantum of energy to get to the level above or below Spacing between the energy levels are not even Electrons cannot be between levels Vs

Atomic Emission Spectrum This is how we know that energy gain and loss is correct Unique for every element Gaseous atoms emit light when subjected to an input of energy at low pressure If you pass the light through a slit and then a prism you can separate the light into its component frequencies Barium

Look at Tubes Math: c = λ ν c = speed of light = E 8 m/s λ = wavelength in meters ν = frequency in 1/s (aka Hertz Hz)

Wave - Particle Duality All objects exhibit at times a wave - like nature, and at other times, a particle - like nature Depends on experiment Throws a wrench in Bohr model New method of describing the motion of subatomic particles Foundation of quantum mechanics

The Quantum Mechanical Model What we use today Describes location and energy of electrons Do not have a direct orbit around the nucleus Based on probability Electron clouds Electrons have quantized energy levels This still works with atomic emission spectra and quanta

Hog Hilton Sample Problem Book 15 hogs into their rooms 6 th floor ____ ____ ____ _____ _____ 6 th floor ______ 5 th floor ______ ______ ______ 4 th floor ______ 3 rd floor ______ ______ ______ 2 nd floor ______ 1 st floor ______

Hog Hilton Sample Problem 3d_____ _____ _____ _____ ____ 4s _____ 3p ______ ______ ______ 3s ______ 2p ______ ______ ______ 2s ______ 1s ______

Part 2 Quantum Numbers

Used to describe the location of electrons Electrons can’t have the same quantum numbers

Principle Quantum Number n Describes energy level Position of the electron with respect to the nucleus As n increases = further from nucleus Has positive values (1, 2, 3…)

Azimuthal Quantum Number l Describes the sublevel Shape of the orbital l = 0 = s orbital = spherical cloud l = 1 = p orbital = dumbbell cloud l = 2 = d orbital = clover cloud l = 3 = f orbital = forget it! Number of sublevels = n Has values 0 to (n-1)

Shapes

Magnetic Quantum Number m l Describe the orbital and its orientation Has values –l to l Orbital shapes within sublevels = n 2 # of electrons = 2n 2

Spin Quantum Number m s Describes the direction of the electron’s spin within a given orbital Has a value of ½ or -½

Example What orbital corresponds to n=2, l = 1, m l = 0? Energy level = 2 Sublevel = p Orbital orientation = y Orbital = 2p y

Quantum Numbers Sum-Up What are the four quantum numbers and what do they indicate? Principle Quantum Number (n): energy level Azimuthal Quantum Number (l): sublevel and shape Magnetic Quantum Number (m l ): orientation of orbital Spin Quantum Number (m s ): direction of spin If an element has n=3, what are the possible l values? What are the possible m l values? l=0, 1, 2 m l =0; m l =-1, 0, 1; m l =-2, - 1, 0, 1, 2 What orbital corresponds to n=4 and l=2 4d

Example What orbital corresponds to n=4, l = 2, m l = -1? Energy level = 4 Sublevel = d Orbital orientation = yz Orbital = 4d yz

Putting it All Together Principle Quantum # # of sublevels Names of sublevels Orbital shapes within sublevels (with total number) # of electrons

Putting it All Together Principle Quantum # (n) # of sublevels (n) Names of sublevels Orbital shapes within sublevels (with total number) (n 2 ) # of electrons (2n 2 ) 11SS (1)2 22S pS Px Py Pz (4)8 33S p dS Px Py Pz Dxy Dxz Dyz Dx 2 -y 2 Dz 2 (9) 18 44S p d fS ppp ddddd fffffff (16)32 55S p d f (g)S ppp ddddd fffffff ggggggggg (25) 50 66S p d f (gh) + hhhhhhhhhhh (36)72 77S p d f (ghi)+ iiiiiiiiiiiii (49)98

Part 3 Rules of Electron Configuration

Aufbau Principle Electrons enter orbitals of lowest energy first Orbitals within a sublevel have equal energy Exceptions  Cr  Cu Which hog rule is this?

Pauli Exclusion Principle An atomic orbital may only hold two electrons Electrons must have opposite spin Clockwise or counterclockwise Denoted with arrows Prevents two electrons from having same quantum numbers Which hog rule is this?

Hund’s Rule Every orbital of the same energy is singly occupied before any orbital is doubly occupied Electrons have the same spin Second electrons are added so the two electrons have opposite spins Which hog rule is this?

Part 4 Writing Electron Configurations

Electron Configuration Diagonal Rule

Electron Orbital Diagram 3d ___ ___ ___ ___ ___ 4s ___ 3p ___ ___ ___ 3s ___ 2p ___ ___ ___ 2s ___ 1s ___

Filling Electron Orbitals 3d ___ ___ ___ ___ ___ 4s ___ 3p ___ ___ ___ 3s ___ 2p ___ ___ ___ 2s ___ 1s ___

Hog Hotel Continue working on your hog hotel using electron configurations.

My Hand Hurts! Write the electron configuration for Barium. Wait… Noble gas/short hand configuration: Find the nearest noble gas that came before the element you are interested in Write the symbol of that noble gas in [brackets] Write the configuration as normal from there on

Part 5 Connecting What We’ve Learned

On the table Mendeleev didn’t know quantum numbers Table is related to how electrons fill the levels in the different shells Blocks s block Groups 1 and 2 p block Groups d block Transition elements f block Inner transition elements

Please complete: “Patterns in Electron Configuration”

Columns Elements have similar properties Why? Similar ground state electron configurations Examples Noble gases  Complete sublevel  Favorable - do not react Halogens  One electron short of completely filled sublevel  Readily react with elements who have a single electron