Topic: Atomic Structure Aim: How are electron PELs further divided Topic: Atomic Structure Aim: How are electron PELs further divided? Do Now: Construct a Lewis Dot diagram for Si. HW:

Remember when… …we talked about PELs? What can you tell me about them? …you learned electron configurations? Let’s modify this model…

PELs can be divided PEL # is only PART of the e- configuration of an element PELs divided into sublevels Sublevels are named with letters (s, p, d, or f) The # of sublevels a PEL can have is equal to the # of the PEL So… PEL 1 has 1 sublevel, PEL 2 has 2 sublevels, etc. PELs higher than 4 would contain more than 4 sublevels – haven’t been named yet.

Sublevels within PELs PEL 1, 1 sublevel, s PEL 2, 2 sublevels, s and p PEL 3, 3 sublevels, s, p, and d PEL 4, 4 sublevels, s, p, d, and f

d is double dumbbell and/or donut Shapes of Sublevels s is spherical p is pair of lobes along x, y, or z axis y d is double dumbbell and/or donut

Orbital & Electron Capacity for Sublevels Sublevels & Orbitals Sublevels are divided into orbitals (increasing odd numbers, so s has 1, p has 3, d has 5, f has 7) Each orbital can contain 2 electrons Orbital & Electron Capacity for Sublevels Sublevel # of Orbitals Max # of e- s 1 2 p 3 6 d 5 10 f 7 14

Orbitals & Electron Capacity PEL Sublevel type # of orbitals per type # of orbitals per PEL Max # of electrons 1 s 2 4 8 p 3 9 18 d 5 16 32 f 7 } } }

Electron Configurations Show how the electrons fill the orbitals in the PEL sublevels 3 rules… 1. Aufbau principle – e- enter orbitals w/the lowest energy first (so start w/the 1s) 2. Pauli exclusion principle – max of 2 e- per orbital, each w/opposite spins ↑ or ↓ 3. Hund’s rule – when e- occupy orbitals of equal energy, they don’t pair up until they have to

Hydrogen Atomic #1, 1 electron Goes in 1s Electron configuration 1s1 There is 1 electron in the 1st PEL, s sublevel 1 s 1 ↑  arrow indicates spin

Helium Atomic #2, 2 electrons Goes in 1s (it can hold 2 electrons, remember) Electron configuration 1s2 There are 2 electrons in the 1st PEL, s sublevel 1 s 2 ↑↓  arrows indicate spin

Lithium Atomic #3, 3 electrons Goes in 1s, then 2s Electron configuration 1s2 2s1 There are 2 electrons in the 1st PEL, s sublevel, 1 electron in the 2nd PEL, s sublevel Total of superscripts must equal total # of electrons 1 s 2 ↑↓ 2 s 1 ↑ .

Beryllium Atomic #4, 4 electrons Goes in 1s, then 2s Electron configuration 1s2 2s2 There are 2 electrons in the 1st PEL, s sublevel, 2 electrons in the 2nd PEL, s sublevel 1 s 2 ↑↓ 2 s 2 ↑↓

Boron Atomic #5, 5 electrons Goes in 1s, then 2s, then 2p Electron configuration 1s2 2s2 2p1 There are 2 electrons in the 1st PEL, s sublevel, 2 electrons in the 2nd PEL, s sublevel, 1 electron in the 2nd PEL, p sublevel 1 s 2 ↑↓ 2 s 2 ↑↓ 2 p 1 ↑ . . .

Carbon 1 s 2 ↑↓ 2 s 2 ↑↓ 2 p 2 ↑ . ↑ . . Atomic #6, 6 electrons Goes in 1s, then 2s, then 2p Electron configuration 1s2 2s2 2p2 There are 2 electrons in the 1st PEL, s sublevel, 2 electrons in the 2nd PEL, s sublevel, 2 electrons in the 2nd PEL, p sublevel BUT – the two 2p electrons go into 2 different orbitals! They DON’T PAIR UP unless they have to! 1 s 2 ↑↓ 2 s 2 ↑↓ 2 p 2 ↑ . ↑ . .

Nitrogen What would this look like? Electron configuration 1s2 2s2 2p3

Oxygen What would this look like? Electron configuration 1s2 2s2 2p4

Rvw - Orbitals & Electron Capacity PEL Sublevel type # of orbitals per type # of orbitals per PEL Max # of electrons 1 s 2 4 8 p 3 9 18 d 5 16 32 f 7 } } }

Orbital Notation: Elements 1-10 Pauli exclusion principle – max of 2 e- per orbital, each w/opposite spins ↑ or ↓ Hund’s rule – when e- occupy orbitals of equal energy, they don’t pair up until they have to

Elements 11-18…

Continuing… Elements continue to fill PEL sublevels & orbitals in this fashion… …until… POTASSIUM. That jerk. Look @ K’s electron configuration on Periodic Table 2-8-8-1 Why isn’t it 2-8-9? The 3rd PEL can hold more than 8 electrons (can hold up to 18)

Reason Aufbau principle – e- enter orbitals w/the lowest energy first Sometimes, low energy portions of higher PELs overlap into high energy portions of lower PELs Huh? I show you.

Potassium e- config: _______________________ basic e- config: _____________

Calcium e- config: _______________________ basic e- config: _____________

Scandium e- config: _______________________ basic e- config: _____________

Titanium e- config: _______________________ basic e- config: _____________

HOW DO YOU KNOW WHICH SUBLEVELS GET FILLED FIRST? Use the Periodic Table!

http://www. wwnorton. com/college/chemistry/gilbert/overview/ch3 http://www.wwnorton.com/college/chemistry/gilbert/overview/ch3.htm#electron_configuration “electron configuration tutorial”