Humboldt State University ® Department of Chemistry

Richard A. Paselk

Chem 109 - General Chemistry - Spring 2015

Lecture Notes 25: 30 March


DEMONSTRATION: Look at Alkali metals, properties and reaction with water (Li, Na, K); Look at the elements of Period 3 (Na - Cl) Note how their properties change from metallic to non-metallic; Look at Halogens (Cl, Br, I [warm to vaporize crystals]).

Electronic Configurations & Periodicity

There are a number of different notation conventions for electronic configurations:

Spectroscopic notation

Note that when we get to the d electrons they are added to the next inner orbital - they are added inside the atom and are not outermost! Note also that you may write them in the order they show up on the Periodic Table, or, if you prefer, you may group them by shell. You may also wish to use a tool to help you remember this pattern of filling:

The Aufbau Principle

Orbital Filling Diagrams



Syllabus / Schedule
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© R A Paselk

Last modified 30 March 2015