Orbital Notation and Electron Configuration October 20th

Distance From The Nucleus  Called the Principle Quantum Number (n)  Describes the principle energy level  n = 1, 2, 3  Called the Principle Quantum Number (n)  Describes the principle energy level  n = 1, 2, 3

Shape of the Orbital  Described by Orbital quantum number (l)  Tells you the shape of the orbital the electron is in  Is it an s, p, d, or f orbital?  Described by Orbital quantum number (l)  Tells you the shape of the orbital the electron is in  Is it an s, p, d, or f orbital?

Position in 3D Space  Described by Magnetic Quantum Number (m)  Indicated the position of the orbital around the 3 axes (x, y, z)  Described by Magnetic Quantum Number (m)  Indicated the position of the orbital around the 3 axes (x, y, z)

Electron’s Spin  The direction of the electron’s spin is described by the spin quantum number  Electrons can be either up or down  When electrons are part of a pair, they must spin in opposite directions  The direction of the electron’s spin is described by the spin quantum number  Electrons can be either up or down  When electrons are part of a pair, they must spin in opposite directions

Pauli Exclusion Principle  No two electrons in the same atom can have the same four quantum numbers (the same description)  No two electrons can have the same address  Electrons are repulsed by each other, so they cannot live together… Hence makes sense they have opposite spins!  No two electrons in the same atom can have the same four quantum numbers (the same description)  No two electrons can have the same address  Electrons are repulsed by each other, so they cannot live together… Hence makes sense they have opposite spins!

Review Of Energy Levels  n = 1  s orbital (2 electrons)  n = 2  s orbital (2 electrons)  p orbital (6 electrons)  n = 3  s orbital (2 electrons)  p orbital (6 electrons)  d orbital (10 electrons)  n = 4  s orbital (2 electrons)  p orbital (6 electrons)  d orbital (10 electrons)  f orbital (14 electrons)  n = 1  s orbital (2 electrons)  n = 2  s orbital (2 electrons)  p orbital (6 electrons)  n = 3  s orbital (2 electrons)  p orbital (6 electrons)  d orbital (10 electrons)  n = 4  s orbital (2 electrons)  p orbital (6 electrons)  d orbital (10 electrons)  f orbital (14 electrons)

3 Rules for Electron Configuration 1) Aufbau Principle - electrons occupy the orbitals of lowest energy first 2) Pauli Exclusion Principle - no two electrons can have the same address(same 4 quantum #s) 3) Hund’s Rule - Electrons try to occupy different orbitals before pairing up 1) Aufbau Principle - electrons occupy the orbitals of lowest energy first 2) Pauli Exclusion Principle - no two electrons can have the same address(same 4 quantum #s) 3) Hund’s Rule - Electrons try to occupy different orbitals before pairing up

Orbital Notation order in which electrons are filled

The Order in which orbitals fill…

Orbital Notation

Arrangement of Electrons in Atoms  Each orbital can be assigned no more than 2 electrons!  Each orbital can hold a pair of electrons per orientation  s1 orientation(pair) 2 electrons  p3 orientations 6 electrons  d5 orientations 10 electrons  f7 orientations 14 electrons  Each orbital can be assigned no more than 2 electrons!  Each orbital can hold a pair of electrons per orientation  s1 orientation(pair) 2 electrons  p3 orientations 6 electrons  d5 orientations 10 electrons  f7 orientations 14 electrons

Orbital Diagram _____ 1s __________ _____ _____ 2s 2px 2py 2pz __________ _____ _____ _____ _____ _____ _____ _____ 3s 3px 3py 3pz 3d _____ _____ _____ _____ _____ _____ _____ _____ _____ 4s 4px 4py 4pz 4d _____ _____ _____ _____ _____ _____ _____ _____ _____ 5s 5px 5py 5pz 5d _____ 6s

How Orbitals Fill…. _____ 1s __________ _____ _____ 2s 2px 2py 2pz __________ _____ _____ 3s 3px 3py 3pz _____ 1s __________ _____ _____ 2s 2px 2py 2pz __________ _____ _____ 3s 3px 3py 3pz

Electron Configuration – Strontium _____ 1s __________ _____ _____ 2s 2px 2py 2pz __________ _____ _____ _____ _____ _____ _____ _____ 3s 3px 3py 3pz 3d _____ _____ _____ _____ _____ _____ _____ _____ _____ 4s 4px 4py 4pz 4d _____ _____ _____ _____ _____ _____ _____ _____ _____ 5s 5px 5py 5pz 5d _____ 6s

Valence electrons are electrons in the outermost energy level of an atom. _____ 1s __________ _____ _____ 2s 2px 2py 2pz __________ _____ _____ 3s 3px 3py 3pz Valence electrons Example: Sulfur

Practice on your own!  Draw the orbital diagram for Calcium  Draw the orbital diagram for Silicon  Draw the orbital diagram for Calcium  Draw the orbital diagram for Silicon

Electron Configuration 1 1 s Energy Level Subshell (s, p, d, f) no. of electrons for H, atomic number = 1

Electron Configuration  Fortunately! Its like orbital diagrams but without drawing the orbitals…  Fill electrons into lower energy levels first  Follow order of filling  Remember how many electrons each level can hold: s holds 2, p holds 6, d 10, f 14  Fortunately! Its like orbital diagrams but without drawing the orbitals…  Fill electrons into lower energy levels first  Follow order of filling  Remember how many electrons each level can hold: s holds 2, p holds 6, d 10, f 14

Examples  Helium: 1s 2  Boron : 1s 2 2s 2 2p 1  Magnesium: 1s 2 2s 2 2p 6 3s 2  Bromine: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5  Helium: 1s 2  Boron : 1s 2 2s 2 2p 1  Magnesium: 1s 2 2s 2 2p 6 3s 2  Bromine: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5

1s 1 1s 2 2s 2 2p 6 3s 1 1s 2 2s 2 2p 6 3s 2 1s 2 2s 2 2p 6 3s 2 3p 5 1s 2 2s 2 2p 6 3s 2 3p 6 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 3 Practice on your own! Hydrogen Sodium Magnesium Chlorine Argon Arsenic

 Octet rule - all elements want to have a full set of valence electrons  Atoms will lose or gain electrons in trying to achieve a full octet  Octet rule - all elements want to have a full set of valence electrons  Atoms will lose or gain electrons in trying to achieve a full octet Octet Rule

Octet Rule states that atoms will gain or lose electrons to achieve a full outermost energy level. This is usually 8 electrons (s 2 p 6 ). Example: Oxygen _____ 1s __________ _____ _____ 2s 2px 2py 2pz O Octet Rule