Lecture notes: CHEM103 – October 16, 2008

0) Review: outer, core & valence electron

1) Electronic configuration of ions

2) Periodic trends: based on electronic structure

Atomic radius

Ionic radius

Ionization energy

Electron affinity

FACTORS INFLUENCING PERIODIC TRENDS AND EXCEPTIONS!

Nuclear Charge

Number of electron shells

Effective nuclear charge

(Number of electron sub-shells)

(Electron-electron repulsion)

Electron configuration of ions

“s” & “p” blocks (main group elements): removal (or addition of) electrons in the valence shell

è to achieve a fully-filled sub-shell!

Examples: Na à Na⁺ ; Ca à Ca²⁺ ; Cl à Cl^– ; Rb à ? ; O à ?

NOTE: THIS ALLOWS US TO PREDICT THE CHARGE ON ANY (monatomic) ION! -- MORE DETAIL ON THIS COMING UP…

“d” block (transition metal elements): the removal order is DIFFERENT than filling order

IONIZATION ALWAYS REMOVES ELECTRONS FROM THE HIGHEST NUMBERED SHELL FIRST!

examples: Cd²⁺ ; Ag⁺ ; Pb²⁺ , Pb⁴⁺ (also Sn) ; V²⁺ à V⁵⁺ ; Fe²⁺, Fe³⁺

TRENDS IN ATOMIC PROPERIES

BASED ON THEIR LOCATION IN THE PERIODIC TABLE

or simply, “PERIODIC TRENDS”

Primary factors that influence these trends:

1. Nuclear charge (Z – the number of protons)

2. Number of electron shells

3. effective nuclear charge (Z^*)

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

ATOMIC RADIUS (SIZE)

examples…

FIRST IONIZATION ENERGY: (LOSS OF ONE e^–)

examples…