Grade 12 University Chemistry Exam Study Notes

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  • Topic: Atom, Electron, Atomic orbital
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  • Published : January 31, 2013
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Unit 1: Atomic Theory
Summary of Quantum Numbers
Principal quantum number, n: the main electron energy levels or shells (n)| Secondary quantum number, l: the electron sublevels or subshells; tells you orbital shape (0 to n-1)| Magnetic quantum number, ml : the orbital orientation of a sublevel (-l to +l)| Spin quantum number, ms : the electron spin (+1/2 or -1/2)| 1| 0| 0| +1/2, -1/2|

2| 01| 0-1,0,+1| +1/2, -1/2+1/2, -1/2|
3| 012| 0-1,0,+1-2,-1, 0, +1, +2| +1/2, -1/2+1/2, -1/2+1/2, -1/2|

Energy Level Diagrams:

Pauli exlusion principle: no two electrons in an atom can have the same four quantum numbers; no two electrons in the same atomic orbital can have the same spin Aufbau principle: each electron is added to the lowest energy orbital available in an atom or ion Hund’s rule: one electron occupies each of several orbitals at the same energy before a second electron can occupy the same orbital

Energy Level Diagrams for ANIONS:
* Add the extra electrons corresponding to the ion charge to the total number of electrons BEFORE proceeding to distribute the electrons into orbitals Energy Level Diagrams for CATIONS:
* You must draw the energy-level diagram for the corresponding neutral atom first, and then remove the number of electrons (corresponding to the ion charge) from the orbitals with the highest principal quantum number, n * The electrons removes might not be the highest-energy electrons!! Electron Configuration Procedure:

1. Determine the position of the element in the periodic table and the total number of electrons in the atom or simple ion 2. Start assigning electrons in increasing order of main energy levels and sublevels (use the Aufbau diagram or the periodic table shown above) 3. Continue assigning electrons by filling each sublevel before going to the next sublevel, until all of the electrons are assigned 4. FOR ANIONS: add the extra electrons to the total number in the atom 5. FOR...
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