CHAPTER 2 Flashcards
(58 cards)
bond where Electrons are unequally shared,more negative charge found closer to one atom.
Due to difference in electronegativity of atoms involved in bond.
polar bond
What makes water polar
The structure of water. Oxygen has a partial negative charge, and the hydrogens have a partial positive charge. The uneven distribution of charge gives rise to the large dipole moment of water.
The dipole moment in this figure points in the direction from negative to positive, the convention used by physicists and physical chemists; organic chemists draw it pointing in the opposite direction. The van der Waals radius is the effective distance
between an atom’s nucleus and its electronic surface, whether the atom is alone or part of a molecule
a measure of the force of an atom’s attraction for electrons it shares in a chemical bond with another atom
Electronegativity
is most electronegative element
Fluorine
Molecules such as ___________ have polar bonds but, given their geometry, are nonpolar molecules; that is, they have a zero dipole moments
CO2
Bonds that are Held together by positive and negative ions
Ionic Bonds
interaction where attraction that occurs when oppositely charged molecules are in close proximity.
Salt Bridge
(1) interactions between lewis A and lewis B that interact via covalent bonds or (2) electrostatic interactions via ionic bonds.
Salt Bridge
When ions in solution intreract with molecules with dipoles, e.g., KCl dissolved in H2O
Ion-dipole interactions
attraction and repulsions between atoms, molecules, as well as other intermolecular forces.
bonds that do not involve electrostatic interactions
for nonpolar
van der Waals Forces
Forces that occur between molecules with dipoles, one positive and one negative
Dipole-dipole interactions
a weak attraction between a polar molecule and a nonpolar molecule. The polar molecule’s permanent dipole creates a temporary dipole in the nonpolar molecule.
Dipole induced-dipole interactions
Hydration Shells Surrounding Ions in Water
Ionic bonds become replaced by ion–dipole interactions. In ionic solids, ionic bonds hold the cations and anions together.
In aqueous solution, these ionic bonds are replaced by ion–dipole interactions. The negatively charged chloride ions are attracted to the partial positive charges on water. The positively charged sodium ions are attracted to the partial negative charges on the water.
Water surrounding ions of this type are called
hydration shells
Ion-dipole and dipole-dipole interactions help __________ and _________ compounds dissolve in water
ionic, polar
what interaction happens when
A polar molecule, such as water, can induce a dipole in a nonpolar molecule, such as oxygen, by distorting the molecule’s electron cloud.
Dipole–induced dipole interaction.
Momentary attractions and repulsions between nuclei and electrons create
induced dipoles and lead to a net stabilization due to attractive forces.
Induced Dipole-Induced Dipole Interactions or London Dispersion Forces
The dipole of water induces a dipole in O2 by __________ the O2 electron cloud.
distorting
Bond Type ranked by strength
strongest
Covalent (C—H)
Covalent (O—H)
Ionic interactions
Ion–dipole
Hydrogen bonds
Van der Waals interactions
weakest
water-loving
tend to dissolve in water
Hydrophilic
water-fearing
tend not to dissolve in water
Hydrophobic
has characteristics of both properties of Hydrophobic and Hydrophilic
molecules that contain one or more hydrophobic and one or more hydrophilic regions, e.g., sodium palmitate
Amphipathic
Examples of Hydrophilic Substances
Polar covalent compounds (e.g., alcohols
such as C2H5OH [ethanol] and ketones
such as (CH3)2CwO [acetone])
Sugars
Ionic compounds (e.g., KCl)
Amino acids, phosphate esters
Examples of Hydrophobic Substances
Nonpolar covalent compounds (e.g.,
hydrocarbons such as C6H14 [hexane])
Fatty acids, cholesterol
