Chapter 12 Intramolecular Forces

Chapter 12 Intramolecular Forces - 1 Chem 1AA3 Department...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1 Chem 1AA3 Department of Department of 1 Chemistry Chemistry CHEM 1AA3: Intro. Chemistry II Ch.12: Liquids, Solids & Intermolecular Forces 2 Chem 1AA3 Chapter 12 Exclude: sections 12.7-12.9 Include: sections 12.1(only capillary action),12.2-12.6 (much of which was discussed in Chem 1A03 recall: properties of water) Intermolecular Forces = IMF 3 Chem 1AA3 In pure substances: van der Waals forces e.g., iodine Dipole-dipole forces e.g., acetone Hydrogen-bonding forces e.g., water In solutions we also see: Ion-dipole forces e.g., hydrated ions Ionic interactions e.g., hydrated ions 12.5 & 12.6: Intermolecular Forces 4 Chem 1AA3 12.5: van der Waals forces Also called induced dipole-induced dipole forces or London dispersion forces (a) nonpolar molecule, (b) experiences an instantaneous dipole, (c) which induces a dipole in its neighbour. Instantaneous dipoles propagate throughout the sample Force strength depends on polarizability (the tendency for charge separation to occur). Fig. 12-24, p. 490 5 Chem 1AA3 12.5: van der Waals forces van der Waals' forces increases with:- atomic number and size of the molecule (due to polarizability)- linear versus branched structures (due to increased intermolecular contact area) Fig. 12-25 Pentane, bp = 36.1 C Neopentane, bp = 9.5 C Table 9-5 (p. 359) Molecule Melting point Cl 2 172 K I 2 387 K 6 Chem 1AA3 12.5: Dipole-dipole forces Occur in polar molecules (molecules with permanent dipoles) polar molecules have bond dipoles and asymmetric shape Being polar increases b.p. over dispersion forces alone e.g., N 2 (77K), NO (121 K), O 2 (90 K) Fig. 12-26 e.g., acetone p. 491 7 Chem 1AA3 12.6: Hydrogen bonding Between an H atom in a polar bond (i.e., H-N, H-O, or H-F) and another electronegative atom (i.e., N, O, or F) One H-bond is small, but many are mighty....
View Full Document

Page1 / 6

Chapter 12 Intramolecular Forces - 1 Chem 1AA3 Department...

This preview shows document pages 1 - 3. Sign up to view the full document.

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