C121 11-3 lec24GL

C121 11-3 lec24GL - Lecture 24 November 4, 2011 Bonding:...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 24 November 4, 2011 Bonding: Specific Models Last Day: I Localized Electron Bonding Models (i) Lewis Structures Rules, Formal Charge,Exceptions,Resonance Today: I Localized Electron Bonding Models (i) Lewis Structures Rules, Formal Charge,Exceptions, Resonance (ii) Valence Shell Electron Pair Repulsion Theory
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Exceptions to the Octet Rule 1. Electron Deficient Species (< octet achieved) (a) Hydrogen Compounds – achieve a duet (2e - ) ex. NH 4 + (b) Group 3A Compounds of B and Al ex. BF 3 (c) Group 2A Compounds of Be ex. BeCl 2
Background image of page 2
Octet Exceptions (cont’d) 2. Odd-Electron Species (odd number of valence electrons) • recall Lewis theory based on bonds formed by sharing electron pairs • odd-electron species place the single (odd) electron such that: (i) formal charges are minimized (ii) octets are not exceeded ex. NO 2 ex. ClO 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Octet Exceptions (cont’d) 3. Octet Exceeded • for elements in period 3 and higher (Z>14), there exist empty, low-energy d-orbitals that can accept “extra” electrons the expanded valence shell means the octet can be exceeded ex. ICl 4 - Note: if more than one atom in a molecule can exceed the octet put “extra” electrons on the central atoms
Background image of page 4
Resonance Structures when you can draw more than one equivalent* Lewis structure for a molecule * equivalent structures have the same arrangement of atoms but different arrangements of electrons ex. CO 3 2- C O O O 2 - : : : C O O O 2 - : : C O O O 2 - ::
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
BUT none of these structures exist! • the “true” representation of the Lewis structure is one in
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 21

C121 11-3 lec24GL - Lecture 24 November 4, 2011 Bonding:...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online