Electron Configurations

Opening Questions: Life on the Edge The atoms below have similar reactivity and chemical behavior. 1. Where are these elements located on the periodic table? 2. What do you think might be responsible for their similar properties?

1 2 13 14 15 16 17 18 1e- 2e- Hydrogen Lithium Sodium 8e- 7e- 4e- 6e- Potassium 3e- 18e- Calcium Gallium Germanium Selenium Krypton Bromine Magnesium Beryllium Aluminum Boron Carbon Nitrogen Oxygen Fluorine 5e- Silicon Sulfur Phosphorus Argon Helium Neon 1 2 13 14 15 16 17 18

Summary: Life on the Edge Core electrons: electrons that are located in all of the inner shells Valence electrons: electrons that are in the outermost shell ONLY Elements with the same # of valence electrons have similar chemical and physical properties. Same group (column)

Summary: Life on the Edge As you move across a row, you add electrons. As you move down a group, you add electron shells. 1e- 2e- Hydrogen Lithium Sodium 8e- 7e- 4e- 6e- Potassium 3e- 18e- Calcium Gallium Germanium Selenium Krypton Bromine Magnesium Beryllium Aluminum Boron Carbon Nitrogen Oxygen Fluorine 5e- Silicon Sulfur Phosphorus Argon Helium Neon 1 2 13 14 15 16 17 18

Check-in: Life on the Edge Provide the following information for element number 34. The element’s name and symbol The number of protons in the nucleus The total number of electrons for this element The number of valence electrons The group number for this element The names of other elements with similar properties

Opening Questions: Shell Game The two drawings show two ways of representing the electron arrangement of calcium (Ca). 1. Name at least two similarities. 2. Name at least two differences.

Electron Shells and Subshells Electrons are first arranged into shells/energy levels labeled n = 1 for the 1st shell, n = 2 for the 2nd shell, etc. Each shell is further divided into subshells designated s, p, d, and f

Electron Shells and Subshells Where do subshells start? s: 1st shell/energy level p: 2nd shell/energy level d: 3rd shell/energy level f: 4th shell/energy level 4

Electron Shells and Subshells Each subshell has a distinct shape

Electron Configuration Notation Electron configuration: a list of all the subshells that contain electrons for a given element electrons occupy lowest energy levels available Notation: 1 number of electrons in subshell 1 s subshell value of energy level

Electron Configurations Which element has the configuration 1s22s22p5?

Electron Configurations Write the electron configuration for this element. How many e- in each subshell? s: 2 electrons p: 6 electrons d: 10 electrons f: 14 electrons

Check-in: Shell Game Identify the element with the following electron configuration. 1s22s22p63s22p64s23d104p3 What is the outermost subshell for bromine, Br? Name an element with electrons in the f-block. What is the electron configuration for the element with the atomic number 13? How many valence electrons does krypton, Kr, have? How do you know?

Shorthand Electron Configurations Instead of writing out all the filled subshells, you can use a shorthand (or noble gas) configuration. Use the last noble gas as your starting point. EXAMPLE: Bromine’s full electron configuration: 1s22s22p63s23p64s23d104p5 Bromine’s shorthand configuration: [Ar]4s23d104p5

Shorthand Electron Configurations Write the shorthand electron configuration for this element Period 1 2 3 4 5 6 7 1s 2s 3s 4s 5s 6s 7s 3d 4d 5d 6d 2p 3p 4p 5p 6p 4f 5f Periodic Table: Subshells 2 elements 10 elements 6 elements 14 elements

PRACTICE! Go Figure Worksheet… Start on the backside: - question #3 b) and d)

D-block Elements Period 1 2 3 4 5 6 7 1s 2s 3s 4s 5s 6s 7s 3d 4d 5d 6d 2p 3p 4p 5p 6p 4f 5f Periodic Table: Subshells 2 elements 10 elements 6 elements 14 elements The d-block elements do not follow the nice pattern seen in groups 1, 2, 13-18. D-block elements tend to have 2 valence electrons because the s-block before them is full. Those s-block electrons are the valence electrons. However, it is possible for the first 5 d-block electrons to be valence electrons.