Electron Location: Part III Electron Configuration

Principle Quantum # (n) LEVEL/SIZE 1234 Angular Quantum # (l) ORBITAL SHAPE or SUBLEVEL ss p s p d s p d f Magnetic Quantum # (m) AXIS/ ORIENTATION or ORBITALS 1 only 1 orbital total orbitals total orbitals total orbitals Spin Quantum # (s) DIRECTION OF ELECTRON SPIN 2 e-8 e-18 e-32 e-

Table 3-6b Orbitals and Electron Capacity of the First Four Principle Energy Levels Principle energy level (n) Type of sublevel Number of orbitals per type Number of orbitals per level(n 2 ) Maximum number of electrons (2n 2 ) 1s112 2 s1 48 p3 3 s1 918 p3 d5 4 s p3 d5 f7

1s 2p 2s 3d 3p 3s 4f 4d 4p 4s 2 (1) 6 (3) 2 (1) 6 (3) 10 (5) 14 (7) 10 (5) = shell & subshell = max. # of electrons = # of electrons = number of orbitals

Principal energy level Number of sublevels Type of sublevel and (# of orbitals) n = 111s n = 222s (1) 2p (3) n = 333s (1) 3p (3) 3d (5) n = 444s (1) 4p(3) 4d(5) 4f (7)

“Rules” for Writing Electron Configurations a method of writing where electrons are found in various orbitals around the nuclei of atoms.  three rules in order to determine this: 1. aufbau principle 2. Pauli exclusion principle 3. Hund’s rule

Aufbau Principle electrons occupy the orbitals of the lowest energy first each written represents an atomic orbital (such as or or or ….) electrons in the same sublevel/shell have equal energy ( ) principle energy levels/shells (1,2,3,4..) can overlap one another  ex: 4s orbital has less energy than a 3d orbital

Pauli Exclusion Principle only two electrons in an orbital  must have opposite spins  represents one electron  represents two electrons in an orbital actually incorrect as well, see next slide Hamster video 1:00

Hund’s Rules every orbital in a subshell must have one electron before any one orbital has two electrons all electrons in singly occupied orbitals have the same spin.

Writing Orbital Diagrams

Orbitals grouped in s, p, d, and f orbitals (sharp, proximal, diffuse, and fundamental) Orbitals grouped in s, p, d, and f orbitals (sharp, proximal, diffuse, and fundamental) s orbitals p orbitals d orbitals f orbitals

ges/Orbital_Energies.jpg Carbon Atomic # - 6

ges/Orbital_Energies.jpg Neon Atomic # - 10

ges/Orbital_Energies.jpg Scandium Atomic # - 21

Writing Electron Configurations To write out the electron configuration of an atom:  use the principal quantum number/energy level (1,2,3, or 4…)  use the letter term for each sub-level (s,p,d, or f); don’t worry about orientation such as x,y,z axis  use a superscript number indicates how many electrons are present in each sub-level hydrogen =1s 1. Lithium =1s 2 2s 1.  don’t write anything for spin

Electron Configurations 2p 4 Energy Level Sublevel Number of electrons in the sublevel 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 … etc.

Order of Electrons 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p

exceptions Cr we would predict: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 4 but it is actually: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5 Cu we would predict: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 9 but it is actually: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 10