Orbital Notations and Electron Configurations 1

2  N = principle energy level 2N 2 = # of e - in N

Finding Orbital Quantum #s on the Periodic Table D Block F Block P Block S Block

Orbital Notation  Shows all four quantum numbers for every electron in the atom.  A box or line is one orbital.  An arrow is one electron.  Spin is designated as “up” or “down”.

Orbital Notation for Silicon  Silicon has 14 electrons, so you will draw 14 arrows. 1s2s 2p 3s 3p

More Examples: 1s2s 2p 3s Magnesium 1s2s2p3s3p4s 3d 1s2s2p3s3p Copper Chlorine

Electron Configurations 7  Shorthand versions of orbital notations.  Does not indicate the magnetic or spin quantum numbers.  Tells the total number of electrons in each SET of orbitals.

Writing an Electron Configuration 8  Write the electron configuration for Neon. 1221s22s22p61221s22s22p6 Principle Quantum Number Orbital Quantum Number Total Number of Electrons

Your Turn 9  Write the electron configuration for Potassium.  Write the electron configuration for Copper  Write the electron configuration for Bromine

Answers 10  Potassium 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1  Copper 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 9  Bromine 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5

Excited State Electrons 11  You can also draw and recognize elements with electrons in the excited state from an electron configuration.  For example: What element is shown? 1s 2 2s 2 2p 6 3s 1 3p 1

What did you answer? 12  This is NOT Aluminum (Al), this is Magnesium (Mg) in the excited state!!  Why?  Look at the 3s sublevel… 1s 2 2s 2 2p 6 3s 1 3p 1

Configurations for Ions 13  Add or remove the correct number of electrons and write the new configuration.  Cu +2 ion  1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 7  Not 9, because the ion lost 2 electrons (it’s configuration now looks like Cobalt’s.)