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Chemistry States of Matter Intermolecular Forces. CALCULATORS OPTIONAL PERIODIC TABLES RECOMMENDED. Forces between molecules determine things like boiling points and freezing points. They happen between molecules , and there are three major types. Intermolecular Forces.
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ChemistryStates of MatterIntermolecular Forces CALCULATORS OPTIONAL PERIODIC TABLES RECOMMENDED
Forces between molecules determine things like boiling points and freezing points. • They happen between molecules, and there are three major types. Intermolecular Forces
#1. London Dispersion forces weakest of all, caused by motion of e- LDF’s increase as the number of e- increases. Large molecules have lots of LDFs. halogens start as gases; bromine is liquid; iodine is solid – all in Group 7A Dominant intermolecular force in nonpolar molecules. Intermolecular Forces
Occurs when polar molecules are attracted to each other. • 2. Dipole interaction happens in water • positive region of one molecule attracts the negative region of another molecule. #2. Dipole interactions
d+d- d+d- H F H F • Occur when polar molecules are attracted to each other. • Slightly stronger than dispersion forces. • Opposites attract, but not completely hooked like in ionic solids. #2. Dipole interactions
d+d- d+d- d+d- d+d- d+d- d+d- d+d- #2. Dipole Interactions d+d-
…is the attractive force caused by hydrogen bonded to N, O, F • N, O, F are very electronegative, so this is a very strong dipole. • And, the hydrogen shares with the lone pair in the molecule next to it. • This is the strongest of the intermolecular forces. #3. Hydrogen bonding
d- d+ O d+ H d+ d- H H O H d+ Hydrogen Bonding(Shown in water) This hydrogen is bonded covalently to: 1) the highly negative oxygen, and 2) a nearby unshared pair.
H O O H H O H H H H O H H H H O O O H H H Hydrogen bonding allows H2O to be a liquid at room conditions.
London dispersion forces are the weakest • A little stronger are dipole interactions • The strongest is hydrogen bonding • All of these are weaker than ionic bonds Order of Intermolecular attraction strengths