s – Sphere p – Dumbbell d – Clover f - ??? Probability & Orbitals Atomic Orbitals : Plot of Ψ = region (or shape) around the nucleus of an atom where an electron with a given energy is likely  (90%) to be found. Orbital Shapes s – Sphere p – Dumbbell d – Clover f - ???

s p d f (low energy e- to high energy e-) Orbitals & Energy The amount of energy that an electron has determines the kind of orbital it occupies. s p d f (low energy e- to high energy e-) The energy of an electron increases as n (quantum number 1,2,3,4…)  increases. Each quantum or energy level can be divided into sublevels # of sub-levels = # of orbitals (s,p,d,f) per energy level The # of sublevels in each energy level = the quantum number squared (n2) Energy Level (n) # of Sublevels (n2) Energy Level Orbital shape 1 1 :1s (one circular orbital) 2 4 :2s (one circular) & 2p (three dumbell) 3 9 :3s (one circular) & 3p (three dumbell) & 3d (five clover) 4 16 :4s (one circular) & 4p (three dumbell) & 4d (five clover) & 4f (seven ????)

Orbital Diagrams & Electron Configurations Orbital Diagram –visual method of organizing an atom’s electrons in different energy levels and orbitals. Aufbau Principle – electrons enter the orbital of lowest energy level and sublevel available first.        Pauli Exclusion Principle – Each orbital can hold at maximum 2 electrons with opposite spins (cancel magnetic fields). 1 clockwise ( + ½)   & 1 counter clockwise (- ½) Hund’s Rule – Before an electron can be placed in an orbital, all of the orbitals of that sub-level must have at least one electron. Electron Configuration:  the address of electrons in an atom.  

Valence vs. Core Electrons Valence Level: the highest (furthest from the nucleus) energy level (n=1, n=2…..) Valence Electrons:  electrons in the s and p orbitals in the highest energy level 1s22s22p63s23p64s2 Octet :   8 valence electrons (full s and p orbitals in the highest energy level) ** Elements with an Octet are chemically stable! ** Will not react with other matter 1s22s22p63s23p6 Core Electrons: All other electrons in the configuration beside valence electrons             1s22s22p63s23p64s2               

[Ne] 3s2 3p6 Short Hand Electron Configuration Write symbol in brackets of [noble gas] (last column on the right of the periodic table) before element. Write the configuration from noble gas to your element! For Carbon – 6 electrons : Long Hand –  1s2 2s2 2p2 Short Hand    [He] 2s2 2p2 For Calcium – 20 electrons : Long Hand –   1s2 2s2 2p63s2 3p64s2 Short Hand -   [Ar] 4s2 For Argon – 18 electrons: Long Hand - 1s2 2s2 2p63s2 3p6 Short Hand – [Ar] ? [Ne] 3s2 3p6

The 4 Orbital “Blocks” on the Periodic Table

Ions & Electron Configurations What is lowest Ionization Energy path to octet? IE = energy needed to remove valence electron Sodium – Na (IE = 9.394 V) 1s22s22p63s1 Sodium ion – Na1+ 1s2 2s2 2p6 Fluorine – F (IE = 17.422 V) 1s22s22p5 Fluorine ion – F1- 1s22s22p6 Isoelectric – ions with the same electron configuration as their nearest noble gas.