Chmy 121in 1st Edition Lecture 12Current LectureReview- Bohr’s model/Theoryo In Bohr’s model, electrons orbit the nucleus like planets around the suno Electrons furthest from the nucleus have the most energy most unstable most likely to react- Orbitalso Electron shells Shells are assigned principle quantum numbers (n=1,2,3…) Each shell has a different number of electrons it can hold, equal to 2n2o Electrons generally occupy the lowest shell available AKA ground state- Concept Checko T or F? Orbitals occupy more space as n increases o If n increases and the size increases, how do you expect this to affect the number of electrons a shell can hold? Each shell can hold 2n2 electronsToday’s Lecture- Energy Shellso • As you move away from the nucleus, the energy differences between levels is less – Energy level diagrams Shells do not become physically closer- Bohrs Model Predicts Hydrogen Spectrao To determine ground state, put electrons in the lowest energy shells This is the ground state electron configurationo Electron can be excited to higher energy excited stateso Electron can relax to any lower energy shell o Difference between shells determines energy Energy defines color of light- Relaxationo Energy is released during relaxationThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Either light or heat The amount of energy released determines the wavelength (l) of light and therefore the color- Sub shellso • Each shell contains subshellso The number of subshellsdepends on the number ofelectrons in shell – n = 1 has only s n = 2 has s and p n = 3 has s, p and d n = 4 has s, p, d, and f- Electron Configurationo We have a short hand notationfor showing how electrons arearranged in an atom. It is calledthe atom’s electronconfigurationo Arsenic Configurationo ---- Hunds Rule- Octet Ruleo Elements react in such way as to place 8 Electrons In their outermost shello Exceptions H, He(2), Be(4),B(6) Some 3rd period elements have more then 8 Group 4 don’t behave Transition metals don’t really follow the rule- Cheat Cheat Electron Configurations- Summary of Groupso IonsAnnouncements- Homework 3 is open and is due Monday Feb. 16 at 11 pm- Exam Scores are posted to D2L- Next Exam March
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