Today- Thursday December 12th You must be in your assigned seat You have 5 minutes to finish and turn in your homework from Tuesday (# of protons, electrons, and neutrons half sheet) Electron Configurations – Day 1

Review The number of electrons an element has can be found by looking at the atomic number Electrons are locked into certain areas of the electron cloud based on how much energy they have Lower energy electrons are closer to the nucleus Higher energy electrons are further from the nucleus

Energy Levels and Orbitals Electrons are found in specific energy levels Energy levels 1-7 Each energy level is broken down into sublevels called orbitals Different energy levels have different orbitals in them 4 Orbitals: s, p, d, and f

Electrons and Orbitals Each Energy level contains a variety of orbitals Each orbital can hold a specific number of electrons S-orbital can hold up to 2 electrons P-orbital can hold up to 6 electrons D-orbital can hold up to 10 electrons F-orbital can hold up to 14 electrons

Aufbau Principle – Electrons fill up the lower energy levels first, then move on to the higher energy levels 5

Rules for Filling Orbitals Fill from the bottom-up (Aufbau principle) Paired electrons have opposite spin ___ not ___ Fill orbitals singly before doubling up ___ ___ ___ not ___ ___ ___

Fill from the bottom-up (Aufbau principle) Paired electrons have opposite spin ___ not ___ Fill orbitals singly before doubling up ___ ___ ___ not ___ ___ ___

Fill in the electron configuration for Carbon How many electrons does Carbon have? Fill it starting on the bottom, one arrow per electron 8

Fill in the electron configuration for Neon 9

Fill in the electron configuration for Bromine 10

Electron configurations Day two

Review Electrons are located in orbitals in energy levels Electrons fill up orbitals and energy levels from the bottom up, following this order: 1s  2s  2p  3s  3p  4s  3d  4p  5s and so on…

Orbitals and the periodic table Instead of filling out the chart that we did yesterday, we can simply write the electron configuration out instead 1 s Number of energy level orbital no. of electrons in orbital Hydrogen, atomic number = 1

Writing electron configurations Carbon (atomic # 6): 1s22s22p2

How do we do this without the chart??? Our periodic table!

Energy level = Row Number

Starting in the upper left hand corner and going across the table, you can figure out how to write the electron configuration

Practicing using the periodic table to write configurations 1 2 3 4 5 6 7 Ne Ar Kr Xe Lithium Germanium Chlorine

Electron configuration day three

Review Problem: Write the electron configuration for Fluorine (F) Fluorine = 9 electrons = 1s22s22p5 Today we are going to learn a shorter way to write electron configurations!

Shorthand Method We can abbreviate the electron configuration by putting the noble gas that comes before the element in brackets, then write the part of the configuration that comes after the noble gas. What is a noble gas? It is an element that is in the last column/group 18 of the periodic table

Examples Fluorine: Regular configuration = 1s22s22p5 Shorthand configuration [He]2s22p5 Doesn’t save a lot of writing- try Cesium (Cs)? Regular Configuration: 1s22s22p63s23p64s23d104p65s24d105p66s1 Shorthand Configuration: [Xe]6s1