Exam 2 Material Flashcards
Intermolecular Forces- Definition
Definition and 5 factors
Intermolecular Forces
-Force of attraction that occurs between atoms, molecules, and ion due to their proximity in space to each other
-Weaker than intramolecular forces (ionic, covalent, metallic bonds)
-Intermolecular forces “appear” stronger
-Magnitude of charge (formal or partial) affects the strength of the attraction
-Distance affects attraction (need to be close together)
-The stronger the attraction, the more they resist moving or breaking apart
Polarity; How does this affect bonds?
Intermolecular Forces
-Controls the bonds that exist
-Separation of electric charge due to differences in the electronegativty of bonded atoms
-Electron density is not shared equally, which leads to partial + and partial - charges (lower case delta)
- Negative charge lies on the more electronegative atom
-Referred to as a dipole
Ex: H20. H—-O(-)—-H (+)
Oxygen is the more negative atom
These are ALL nonmetals
Polarity; Non-polar and Polar Bonds
Intermolecular Forces
Non-Polar: C-C, C-H, 2 or more of the same atoms
Polar: C-O, C-N, S-C, C-F, C-Cl, C-I, P-O, O-H, N-H, S-H
Application of Intermolecular Forces
Surface Tensions
Intermolecular Forces
-Liquid’s resistance to increase its surface area
-The stronger the intermolecular forces, the more energy required to increase the surface area
-To minimize surface area, liquids form spherical drops
Application of Intermolecular Forces
Capillary Action
Intermolecular Forces
-The spontaneous rising of a liquid in a narrow tube or the movement of a liquid up a piece of paper against the pull of gravity
Application of Intermolecular Forces
Viscosity
Intermolecular Forces
-Measure of a liquid’s resistance to flow
-Increased viscosity = increased energy required
-The amount of energy necessary to move an object through a fluid
-Molecule size plays an important role (greater potential for more intermolecular force interactions)
Application of Intermolecular Forces
Receptor-Drug Binding
Intermolecular Forces
-The vast majority of drug compounds bind to receptors through intermolecular forces rather than through the formation of chemical bonds
-Determines properties such as efficacy, potency, and, to a limited extent, toxicity.
Application of Intermolecular Forces
Phase Changes
Intermolecular Forces
-Representation of the changes in the phase of a substance w/ respect to temperature and pressure
-Energy is required to disrupt molecular interactions and thus lead to changes in the states of matter
-Changes in phase do not break chemical bonds; just cause an interruption of intermolecular forces
Application of Intermolecular Forces
Solubility
Intermolecular Forces
-Depends on attractive forces of the solute and solvent
-Substances with a similar polarity will be soluble
Weakest
Van Der Waals Forces
Intermolecular Forces
Weakest of the molecular forces
Occurs between non-polar bonds
Dipole-Dipole Interactions
Intermolecular Forces
-Occurs in **all **polar molecules
-Relatively strong interaction
Hydrogen Bonding
Intermolecular Forces
OH or NH group
Very strong
-Can have H-bond donors (donating H e-) or H-bond acceptor (accepting H e-)
Ion-Dipole
Intermolecular Forces
-Occurs between a full formal charge & a dipole (N+ and H)
Electrostatic interactions
Intermolecular Forces
-Not common in drugs
-Occurs between non-metals (positive and negative ends are attacted)
-Persist longer than other type interactions
Solutions
Solutions
-Solution: Homogenous mixture of two or more substances
-Solvent: Major component of mixture (water, AQ)
-Solute: Minority component of the mixture (can have multiple of these)
