CHEM101 Lecture Notes - Lecture 12: Periodic Trends, Ionic Radius, Electron Configuration

• School: University of Alberta
• Department: Chemistry
• Course: CHEM101
• Professor: Sai Yiu

Document Summary

Chem 101 - lecture #12 - ionic radii. Na (1s2 2s2 2p6 3s1) na+ (1s2 2s2 2p6) + e- Decreased shielding results in increased zeff: anions. Cl (1s2 2s2 2p6 3s2 3p5) + e- cl- (1s2 2s2 2p6 3s2 3p6) Increased repulsion causes electron to occupy more space. Decrease zeff causes the expansion of ionic size: ionic radius increases down groups, across a period, ionic radius decreases for the cations and increases from cations to anions, the anions size decreases across a period, isoelectronic series. For comparison of ionic sizes, the ions need to have the same electron configurations (isoelectronic) eg na 1s2 2s2 2p6 3s1. Na+ 1s2 2s2 2p6 [ne: mg2+ , f 1s2 2s2 2p5, f- 1s2 2s2 2p6 [ne] eg. 2 arrange the ionic size in order of increasing size of the following ions. Na+, mg2+, al3+, f-, n3-, o2: check electron configuration first.