Electron Configuration

Notebook Setup The title of the notes is “Electron Configuration Cornell Notes.” CROSS OUT the part that says “Cornell Notes.” Cut out the notes and tape them on 136 and 138.

Learning Objectives Apply the Pauli exclusion principle, the aufbau principle, and Hund’s rule to write electron configurations using orbital diagrams and electron configuration notation.

Review of Quantum Numbers Levels Sublevels 1 (1) s 2 (2) s p 3 (3) s p d 4 (4) s p d f

Review of Quantum Numbers Sublevels Orbitals s 1 p 3 d 5 f 7

Electron Configurations Electron configurations are shorthand ways of summarizing how electrons are situated around the nuclei of atoms. There are three basic rules to follow when determining the electron configurations of atoms: aufbau principle Pauli exclusion principle Hund’s rule.

Electron Configurations When you’re filling an atom with electrons, where do you put them?

Aufbau Principle Rule 1: Each electron occupies the lowest energy level available.

Pauli Exclusion Principle Rule 2: Only two electrons per orbital, and they must have opposite spins.

Hund’s Rule Rule 3: In each sublevel, first put one electron in each orbital, then go back and start putting a second electron in each.

Electron Configurations Principal energy level The electron configuration notation designates Principal energy level Energy sublevel Superscript representing the number of electrons in the orbital 1s2 # of electrons in orbital sublevel

Electron Configurations

Electron Configurations STOP

Electron Configurations We’re not going to talk about atoms.

Electron Configurations We are not even going to think about atoms.

Electron Configurations We’re going to book a concert.

Electron Configurations Seating levels further from the stage have more sections

Electron Configurations Seating levels further from the stage have more sections

Electron Configurations Seating levels further from the stage have more sections

STAGE Row 1 Row 2 Row 3 Row 4 Row 5 Section S P D F

STAGE Your ticket says ROW 3 - SEC P - SEAT 2. Where is your seat? Section S P D F Your ticket says ROW 3 - SEC P - SEAT 2. Where is your seat?

STAGE Your ticket says ROW 3 - SEC P - SEAT 2. Where is your seat? Section S P D F Your ticket says ROW 3 - SEC P - SEAT 2. Where is your seat?

Everybody wants to sit as close to the stage as they can. Row 1 Rule 1 Row 2 Row 3 Row 4 Row 5 Everybody wants to sit as close to the stage as they can. -Mr. Aufbau

Seats are in pairs. Every pair of seats can hold only two people. STAGE Row 1 Rule 2 Row 2 Row 3 Row 4 Row 5 Seats are in pairs. Every pair of seats can hold only two people. -Mr. Pauli

STAGE Row 1 Rule 3 Row 2 Row 3 Row 4 Row 5 People would rather sit next to an empty seat. But they will sit next to a stranger if it means they can be in a better section. -Mr. Hund

STAGE Which seats are really closest to the stage? Row 1 Order of filling Row 2 Row 3 Row 4 Row 5 Which seats are really closest to the stage?

STAGE Which seats are really closest to the stage? Row 1 Order of filling Row 2 Row 3 Row 4 Row 5 Which seats are really closest to the stage?

STAGE Row 1 Now let’s fill some seats! Row 2 Row 3 Row 4 Row 5

You sold 25 tickets. STAGE Row 1 Now let’s fill some seats! Row 2

You sold 25 tickets. Which seats are filled? STAGE Row 1 Now let’s fill some seats! Row 2 Row 3 Row 4 Row 5 You sold 25 tickets. Which seats are filled?

STAGE Row 1 Row 2 Row 3 Row 4 Row 5 Section S P D F

STAGE Row 1 Row 2 Row 3 Row 4 Row 5 Section S P D F

STAGE Row 1 Row 2 Row 3 Row 4 3 4 Row 5 Section S P D F

This is the order that you will sell tickets. STAGE Row 1 Row 2 Row 3 Row 4 3 4 Row 5 4 5 Row 6 4 5 Row 7 5 6 This is the order that you will sell tickets.

This is the order that you will sell tickets. STAGE Row 1 Row 2 Row 3 Row 4 3 4 Row 5 4 5 Row 6 4 5 Row 7 5 6 This is the order that you will sell tickets.

This is the order that you will sell tickets. STAGE Row 1 Row 2 Row 3 Row 4 3 4 Row 5 4 5 Row 6 5 6 Row 7 6 7 S D P 4 5 F This is the order that you will sell tickets.

We’re going to hire an usher to be in charge of each row in our chart. STAGE Row 1 Row 2 Row 3 Row 4 3 4 Row 5 4 5 Row 6 5 6 Row 7 6 7 S D P 4 5 F We’re going to hire an usher to be in charge of each row in our chart.

We’re going to hire an usher to be in charge of each row in our chart. STAGE Row 1 Helen Row 2 Neal Row 3 Aaron Row 4 3 4 Kris Row 5 4 5 Xavier Row 6 5 6 Ron Row 7 6 7 Unice S D P 4 5 F We’re going to hire an usher to be in charge of each row in our chart.

We’re going to hire an usher to be in charge of each row in our chart. STAGE Row 1 Helen Row 2 Neal Row 3 Aaron Row 4 3 4 Kris Row 5 4 5 Xavier Row 6 5 6 Ron Row 7 6 7 Unice S D P 4 5 F We’re going to hire an usher to be in charge of each row in our chart.

You sold 25 tickets. STAGE Row 1 Helen Row 2 Neal Row 3 Aaron Row 4 3 4 Kris Row 5 4 5 Xavier Row 6 5 6 Ron Row 7 6 7 Unice S D P 4 5 F You sold 25 tickets.

Which seats are filled? STAGE Row 1 Helen Row 2 Neal Row 3 Aaron Row 4 3 4 Kris Row 5 4 5 Xavier Row 6 5 6 Ron Row 7 6 7 Unice S D P 4 5 F Which seats are filled?

Which seats are filled? 1S2 2S2 2P6 3S2 3P6 4S2 3D5 Row Section Seats Usher 1 S 2 Helen 2 S 2 2 P 6 Neal 3 S 2 3 P 6 Aaron 4 S 2 3 D 5 1S2 2S2 2P6 3S2 3P6 4S2 3D5

Aaron’s row is full, plus 4S2 3D5 Which seats are filled? Row Section Seats Usher 1 S 2 Helen 2 S 2 2 P 6 Neal 3 S 2 3 P 6 Aaron 4 S 2 3 D 5 Aaron’s row is full, plus 4S2 3D5

Which seats are filled? [Ar] 4S2 3D5 Row Section Seats Usher 1 S 2 Helen 2 S 2 2 P 6 Neal 3 S 2 3 P 6 Aaron 4 S 2 3 D 5 [Ar] 4S2 3D5

Try some others! STAGE Row 1 Helen Row 2 Neal Row 3 Aaron Row 4 3 4 Kris Row 5 4 5 Xavier Row 6 5 6 Ron Row 7 6 7 Unice S D P 4 5 F Try some others!

The Periodic Table & Electron Configurations

Sample Problems Divide page 137 in half. Title the top half “Electron Configuration Examples and the bottom half “Electron Configurations for Ions”

Electron Configuration Examples Write the electron configurations for the following elements on the top of page 137. Phosphorus (atomic number = 15) Calcium (atomic number = 20) Strontium (atomic number = 38) 4. Lead (atomic number = 82)

Electron Configurations for Ions Atoms can gain or lose one or more electrons to form ions. An ion is an atom (or group of atoms) that is electrically charged as a result of loss or gain of electrons.

Electron Configurations for Ions An anion is a negatively charged ion. Lets look at the electron configuration for an anion: Cl 1s22s22p63s23p5 Cl- 1s22s22p63s23p6 A cation is a positively charged ion. Lets look at the electron configuration for a cation: Na 1s22s22p63s1 Na+ 1s22s22p6

Electron Configurations for Ions Examples Write electron configurations for the following ions on the bottom of page 137. Cu+ Pb4+ O2- Br-

Orbital Diagram another way to show an atom’s electron configuration Electrons in orbitals can be represented by arrows in boxes. Each box is labeled with the principal quantum number and sublevel associated with the orbital.

Sample Problems Divide page 139 in half. Title the top half “Orbital Diagram Examples” and the bottom half “Noble Gas Shorthand Examples”

Orbital Diagram Examples Draw the orbital diagram associated with each of the following elements on the top of page 139. Phosphorus: 1s22s22p63s23p3 Calcium: 1s22s22p63s23p64s2 Strontium: 1s22s22p63s23p64s23d104p65s2 4. Lead:1s22s22p63s23p64s23d104p65s24d105p66s24f14 5d106p2

Noble Gas Notation Noble gases are the elements in the last column of the periodic table. Noble gases have eight electrons in their outermost orbital and they are very stable (non-reactive).

Noble Gas Notation Noble-gas notation is a method of representing electron configurations of noble gases. The noble-gas notation uses bracketed symbols. [He] helium [Ne] neon

Noble-Gas Notation Compare the electron configuration for neon with sodium’s configuration: Ne: 1s22s22p6 Na: 1s22s22p63s1 Using noble-gas notation, an element’s electron configuration can be shortened. [Ne]3s1

Practice Problem #3 Write the electron configurations for the following elements using noble gas shorthand at the bottom of page 139. Phosphorus (P) Calcium (Ca) Strontium (Sr) Lead (Pb)

Summary The arrangement of electrons in an atom is called the atom’s electron configuration. Electron configurations are defined by the aufbau principle, the Pauli exclusion principle, and Hund’s rule. Electron configurations can be represented using orbital diagrams and electron configuration notation.