Warm-Up Complete the warm-up questions on your practice packet that you grabbed when you came in the room.

Electron Configuration

Electron Configurations Bohr was right. …sort of… Ok so, yes, Bohr was right. Electrons move around the nucleus at certain energy levels, but it’s a little more complicated. Within these levels, we have orbitals, or energy sublevels which are regions where an electron is likely to be found

Remember This? Electron configuration is just a more specific method for identifying the position of electrons

Electron Config. v. Bohr Model

4 electron orbitals: Orbital Shape # of electrons held s Sphere Dumbbell shaped 6 electrons d Balloons tied together 10 electrons f Bracelets 14 electrons

Electrons fill energy levels based on rules from 3 different principles. Kind of like a stadium!

Aufbau Principle Aufbau is German for “building up, construction” Courtesy of Bohr, electrons fill up energy levels like stadium seats Lowest level first!

Pauli Exclusion Principle Each orbital holds up to 2 electrons “Two to a seat!” The electrons in those “pairs” have to spin in different directions “Makes ‘em fit!”

Hund’s Rule Electrons fill orbitals with the same spin first. Then they “buddy up” Because if you could have a seat to yourself, you’d take that before having to cram in with someone else! Right?

Looking at our “stadium”… 4p 4s 3d 3p 3s Increasing Energy 2p 2s 1s

Drawing Electron Configuration Lithium (Li)

Nitrogen (N)

Neon (Ne)

Sodium (Na)

We could draw these pictures every time…. Or we could learn shorthand! Example: 1s22s22p4 (What you drew in your picture).

Electron Configuration We do not want to draw out all those boxes, so we have a more efficient means of doing it. We write out electron configurations for elements in a more condensed, shorthand manner.

It’s like finding the street address of an element…. 1. Number of electrons (number of steps) 2. What neighborhoods you have to go through (s, p, d, f) 3. How many houses are in each neighborhood?

Helium’s Electron Address

Carbon’s Electron Address 1. Number of electrons (number of steps) 2. What neighborhoods you have to go through (s, p, d, f) 3. How many houses are in each neighborhood?

Let’s Break it Down! Step 1: Find total number of electrons. In a neutral atom, number of electrons = number of protons (atomic number) Step 2: Count up using the periods and blocks of the periodic table. Each time you get to a new row or block, count the number of electrons.

Final Step Step 3: Write in the following format: 1 s 2 Number of Electrons Period (row number) Energy Sub-level (Block)

Let’s Do It! (Whiteboards) Diagram the electron configuration for Magnesium (Mg) Diagram the electron configuration for Silver (Ag)

Let’s Practice… Lithium Oxygen Boron Identify the element…. 5 minutes. Work in your table groups. Be prepared to share your answers with the class.

Exit Ticket (On the back) 1) How many orbitals make up the 4d subshell? (Remember: Each orbital holds 2 electrons) a) 0 b) 1 c) 3 d) 5 e) 7. 2) How many electrons are held in a p subshell? a) 1 b) 2 c) 3 d) 6 e) 10