Lecture notes: CHEM103 Fall 2008 – October 14

LECTURE OUTLINE:

0) Review: How do electrons “fill” an atom?

Madelung’s rule

aufbau principle
Pauli exclusion principle

Hund’s rule

How do you write electronic configurations of neutral atoms?

“spdf” notation (text only with sub- & super-scripts)

abbreviated “spdf” notation (using Noble gases)

orbital box notation (boxes or lines w/arrows)

energy level notation

1) Exceptions to filling order in transition metals

2) Define: outer, core & valence electron

3) Electronic configuration of ions

4) Periodic trends: based on electronic structure

Atomic radius

Ionic radius

Ionization energy

Electron affinity

FACTORS INFLUENCING PERIODIC TRENDS AND EXCEPTIONS!

Effective nuclear charge

Number of electron shells

Number of electron sub-shells

Electron-electron repulsion

Check out: http://center.acs.org/periodic/tools/PT.html

EXCEPTIONS to typical filling order (back to HUND’S RULE)

transition metals: e.g. Cu; Mo

principle: electrons repulse (repel) each other

DEFINITION: “outer electron”

electrons having the highest value of “n” (for the ground state) of any atom

DEFINITION: “core electron” or “inner electron”

electrons INSIDE (lower in energy than) the outer electrons

DEFINITION: “valence electron”

FOR MAIN GROUP ELEMENTS: electrons in outermost s (and possibly p) sub-shell

FOR TRANSITION METAL ELEMENTS: generally, ALSO includes electrons in the outermost (n-1) d sub-shell

These DETERMINE REACTIVITY and the way elements combine to form compounds!