Electron configuration: is how electrons are organized within atoms. 4p 3d 4s s 1 2 3 4 5 6 1 2 p 1 3p 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Electron configuration: is how electrons are organized within atoms. 1s

Rules of Electron Configuration:  Aufbau principle: Electrons enter orbitals of lowest energy first.  Pauli exclusion principle: An atomic orbital may describe at most two electrons  Hund’s rule: When electrons occupy orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with parallel spins.

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 OK, so we’re going to use arrows pointing up or down to represent the electrons. Can you guess into which box the first electron would go given that it is attracted to the nucleus? 1s

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s H f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s1 That’s right: it goes in the 1s sublevel. And its el. config is 1s1. Notice in the table above where H is – in the area designated as 1s. So where does the next electron go? 1s

Electron Configuration: Shorthand Notation: -Coefficient: energy level -Lower case letter: type of subshell -Superscript: # of electons in subshell

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s He f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 If you were thinking it went in the 2s, then you forgot that each orbital can hold up to two electrons. Note how He is right here in the area designated as 1s2 and so its el. config. is 1s2. 1s

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Li f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s1 Now that the 1s is filled, the next electron goes in the next sublevel – the 2s. Again note how Li is in 2s1. 1s Its full el. conf. is 1s2 2s1. What is Be’s el. conf?

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Be f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 Is this what you were thinking? Good. Now look at the periodic table above, what comes after the 2s sublevel? 1s The 2p sublevel. So what will the next el. conf. be?

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s B f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p1 Is this what you were thinking? Notice how B is in the 2p1 spot. 1s So its full el. conf. is 1s2 2s2 2p1. What’s next?

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s C f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p2 Is this what you were thinking? Notice how C is in the 2p2 spot. So its el. conf. is 1s2 2s2 2p2 1s Notice also how when we fill a sublevel…

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s N f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p3 …we put one electron in each orbital until the sublevel is half filled… 1s

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s O f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p4 … and then we go back and start pairing off 1s This is called “Hund’s Rule, but it also referred to as the bus seat rule. Can you figure out why?

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s F f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p5 Look at F. It’s just one electron away from having filled 2p sublevel… 1s And it’s just one square away from the end of the 2p block.

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Ne f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 And then Ne has a completely filled outer level. Na is next. Can you guess where the next electron is going to go? 1s

Na 1s2 2s2 2p6 3s1 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 5 2p 6 7 2s f 1s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Na f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s1 That’s right: in the 3s sublevel. Right now, write down in your notebook what you think the next three el configs will be. 1s

Mg 1s2 2s2 2p6 3s2 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 5 2p 6 7 2s f 1s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Mg f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 Did you get this one right? 1s

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Al f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p1 How about Al’s? See how Al is in the 3p1 spot on the per table 1s and its el config ends with 3p1

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Si f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p2 Now just advance through the next 23 slides, but as you do, make sure you are understanding 1s

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s P f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p3 Exactly what is going on… how the el configs simply follow the sequence of the periodic table. 1s

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s S f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Your goal by the end of this slide show is to be able to write el configs for any element using just the periodic table – and your brain! 1s2 2s2 2p6 3s2 3p4 1s

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Cl f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p5 1s

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Ar f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 1s

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s K f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s1 1s

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Ca f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 1s

Sc 1s2 2s2 2p6 3s2 3p6 4s2 3d1 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 5 2p 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Sc f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d1 1s

Ti 1s2 2s2 2p6 3s2 3p6 4s2 3d2 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 5 2p 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Ti f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d2 1s

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s V f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d3 1s

Cr 1s2 2s2 2p6 3s2 3p6 4s2 3d4 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 5 2p 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Cr f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d4 1s

Mn 1s2 2s2 2p6 3s2 3p6 4s2 3d5 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 5 2p 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Mn f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d5 1s

Fe 1s2 2s2 2p6 3s2 3p6 4s2 3d6 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 5 2p 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Fe f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d6 1s

Co 1s2 2s2 2p6 3s2 3p6 4s2 3d7 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 5 2p 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Co f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d7 1s

Ni 1s2 2s2 2p6 3s2 3p6 4s2 3d8 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 5 2p 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Ni f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d8 1s

Cu 1s2 2s2 2p6 3s2 3p6 4s2 3d9 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 5 2p 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Cu f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d9 1s

4d 5s 4p 3d 4s s 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Zn f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d10 1s

Ga 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Ga f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1 1s

Ge 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Ge f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2 1s

As 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s As f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3 1s

Se 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Se f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4 1s

Br 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Br f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5 1s

Kr 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d 5s 4p 3d 4s s p 1 3p 2 d 3 3s 4 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Kr f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 1s

Rb 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d 5s 4p 3d 4s s p 1 3p 2 d 3 1 2 p 1 3p 1 2 3 4 5 6 2 d 3 3s 1 2 3 4 5 6 7 8 9 10 4 5 2p 6 7 2s Rb f 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 1s

So, the pattern for reading the electron configurations right off the periodic table is this: 1 1s2 2 2s2 2p6 3 3s2 3p6 4 4s2 3d10 4p6 5 5s2 4d10 5p6 6 6s2 5d10 6p6 7 7s2 6d10 4f14 5f14

The short cut would be: [Ne]3s2 3p5 For example, Cl (#17) which is right here on the table: So the answer would be 1s2 2s2 2p6 3s2 3p5 The short cut would be: [Ne]3s2 3p5 1 1s2 2 2s2 2p6 3 3s2 3p5 4 5 6 7

1s2 2s2 2p6 3s2 3p6 4s2 3d8 Short cut: [Ar] 4s2 3d8 1 2 3 4 5 6 7 Or how about Ni (#28) 1s2 2s2 2p6 3s2 3p6 4s2 3d8 Short cut: [Ar] 4s2 3d8 1 1s2 2 2s2 2p6 3 3s2 3p6 4 4s2 3d8 5 6 7

Exceptions: Some configurations don’t follow the Aufbau principle because….

Some configurations don’t follow the Aufbau principle because: Exceptions: Some configurations don’t follow the Aufbau principle because: Filled energy levels are more stable than partially filled ones Half filled ones are more stable than partially filled ones

Exceptions to the Electron Configuration Rules Examples: Chromium Wrong: 1s22s22p63s23p64s23d4 Right: 1s22s22p63s23p64s13d5 Copper Wrong: 1s22s22p63s23p64s23d9 Right: 1s22s22p63s23p64s13d10

Exceptions to the Electron Configuration Rules Example: What is the electron configuration for rubidium? Solution: Rb: 1s22s22p63s23p64s23d104p65s1 Example: What is the electron configuration for silver? Ag: 1s22s22p63s23p64s23d104p65s24d9 (half-filled s level more stable than partially-filled d level)  1s22s22p63s23p64s23d104p65s14d10

ELECTRON CONFIGURATION BATTLESHIP!! Mark 6 ships on your periodic table. One partner will call out the electron configuration notation. The other partner will confirm the element before replying with “hit” or “miss.”