Electron Configuration

Evaluation/ Assessment Objective Today I will be able to: Calculate the electron configuration for elements on the periodic table Evaluation/ Assessment Informal assessment – student responses when reviewing electron configuration problems. Listening to group interactions on practice sheets Formal Assessment – collecting and analyzing responses to electron configuration worksheet 2

Lesson Sequence Warm – Up Explain: How to write electron configurations Elaborate: write electron configurations with a partner for questions 1-18 Evaluate: review the questions as a class (informal assessment) Explain: electron configurations in 3d orbitals and Aufbau diagrams Elaborate: Students will complete 19-36 on electron configuration WS with a partner Evaluate: review the questions as a class (informal assessment) Explain: abbreviated electron configurations Elaborate: Students will add a column to the WS and repeat write the abbreviated configuration Evaluate: Abbreviated configurations will be reviewed as a class (informal assessment) Exit Ticket

Warm - Up According to the modern atomic theory (Schrodinger’s model) where are the electrons located? According to the Bohr model, where are the electrons located?

Objective Today I will be able to: Calculate the electron configuration for elements on the periodic table

Homework Have a great afternoon! 

Agenda Warm – Up Electron Configuration Notes Electron Configuration Practice Exit Ticket

Electron Configuration

Label and color your periodic table to match the periodic table on the next slide…

Electron Configuration 1 2 3 4 5 6 7 p-block s-block d-block n-1 f-block n-2

Electron Configuration “address” of where each individual electron is located in an atom 1s2 Number of electrons in the orbital Energy Level (n) Orbital

(Principal) Energy Level Symbol = n As atoms get bigger, there are more electrons, therefore more energy levels Fill the lowest energy levels first (ground state) Within each energy level, we have one or more sublevels These sublevels are called orbitals

Orbitals Based on modern model of atom 3-D region around the nucleus indicating the probable location of the electron 4 types of orbital (low  high energy) s p d f

Orbital Shapes

Orbitals cont. Each sublevel can hold a specific amount of electrons

Now we can put these ideas together and write an electron configuration for an atom…

Examples Sodium (Na) Cobalt (Co) Has 11 electrons (when neutral) Electron Configuration: 1s22s22p63s1 Cobalt (Co) Has 27 electrons (when neutral) Electron Configuration 1s22s22p63s23p64s23d7

Electron Configuration Practice Complete numbers 1-18

Why does 4s come before 3d? 3d is of slightly higher energy than 4s, but 4s is further from the nucleus It takes less energy for a 3d electron to form pairs then a 4s electron

Aufbau Diagram Instead of using the periodic table as a road map, you can use the aufbau diagram to determine the order that the electrons occupy the different energy levels Electrons fill the lowest energy orbitals first

Aufbau Diagram

Complete Electron Configuration Practice Worksheet 19 - 36

Abreviated Electron Configuration Scientists are lazy  We need a shorthand way to represent electron configuration How do we do this? Noble Gas Configuration

Noble Gas Configuration The last column on the periodic table is referred to as the noble gases To write in abbreviated configuration: Find the last noble gas within the configuration Write the symbol Write the remaining configuration Example Ca - 1s2 2s2 2p6 3s2 3p6 4s2 Noble Gas Configuration = [Ar] 4s2

Noble Gas Configuration Writing Noble Gas Configurations for ions is a little bit different Must account for an electron being gained or lost Chlorine Ion = Cl-1 [Ne] 3s2 3p6 Sodium Ion = Na+1 [He] 2s2 2p6

Electron Configuration Practice Go back and write the Abbreviated (Noble Gas) configuration for the elements on the worksheet on the right hand margin

Visualizing Orbital's of Electrons

z y The 3 axes represent 3-dimensional space x

z y The nucleus of the atom is at the center of the three axes x

The 1s orbital is a sphere, centered around the nucleus

The 2s orbital is also a sphere

The 2s electrons have a higher energy than the 1s electrons. Therefore, the 2s electrons are generally more distant from the nucleus, making the 2s orbital larger than the 1s orbital

There are three 2p orbitals

The three 2p orbitals are oriented perpendicular to each other

z This is one 2p orbital (2py) y x

z Another 2p orbital (2px) y x

z The third 2p orbital (2pz) y x

z 2px y x

z 2px and 2pz y x

z The three 2p orbitals, 2px, 2py, 2pz y x

Once the 1s orbital is filled…

The 2s orbital begins to fill

Once the 2s orbital is filled…

The 2p orbitals begin to fill

Each 2p orbital intersects the 2s orbital and the 1s orbital

Each 2p orbital gets one electron before pairing begins

Once each 2p orbital is filled with a pair of electrons, then…

The 3s orbital gets the next two electrons

The 3s electrons have a higher energy than 1s, 2s, or 2p electrons

3s electrons are generally found further from the nucleus than 1s, 2s, or 2p electrons

Exit Ticket Mol Monday # 1 How many molecules of CO are in 5.0 grams of CO?

Exit Ticket Write the electron configuration of sulfur