Chapter 2: Chemical Bonds and Interactions

Vocabulary flashcards covering chemical bonds, electronegativity, intermolecular forces, and molecular interactions from Chapter 2.

Bond energy

The amount of energy needed to separate two bonded or interacting atoms under physiological conditions.

Intramolecular bonds

Bonds that occur between atoms within a single molecule, such as covalent bonds.

Intermolecular forces

Forces and interactions that occur between separate molecules.

Covalent bond

A strong intramolecular chemical bond formed by the sharing of electron pairs between atoms.

Electronegativity

A measure of the ability of an atom to attract electrons in the context of a chemical bond, evaluated using scales such as the Pauling scale and Mulliken scale.

Polar covalent bond

A covalent bond where shared electrons are pulled more toward the more electronegative atom, resulting in regions of partial negative charge ($\delta^-$) and partial positive charge ($\delta^+$) (e.g., $\text{O-H}$ and $\text{N-H}$).

Nonpolar covalent bond

A covalent bond where electrons are shared equally between two atoms (e.g., $\text{C-C}$, $\text{O-O}$, $\text{N-N}$, and $\text{C-H}$).

Ionic bond

A bond formed by the electrostatic attraction of oppositely charged ions following the transfer of valence electrons.

Cation

A positively charged ion formed when an atom loses one or more valence electrons (e.g., $\text{Na}^+$).

Anion

A negatively charged ion formed when an atom gains one or more valence electrons (e.g., $\text{Cl}^-$).

Salts

Ionic compounds formed by ionic bonds that often tightly pack together to form crystals (e.g., $\text{NaCl}$).

Hydrogen bond

A non-covalent interaction resulting from the attraction between a partial positive charge on a hydrogen atom and a partial negative charge on an electronegative atom (such as oxygen or nitrogen).

Dipole-dipole interactions

Intermolecular attractions or repulsions between molecules containing permanent electrical dipoles.

Ion-dipole interactions

Intermolecular interactions that occur between an ion and a polar molecule, such as during the hydration of $\text{Na}^+$ or $\text{Cl}^-$ in water.

Hydrophobic interactions

The clustering or interaction of nonpolar substances when placed in the presence of polar substances like water.

Van der Waals interactions

Interactions driven by transient electron distributions of nonpolar substances, also referred to as dispersion forces.

Molecular mimic

A molecule (such as morphine) that shares structural similarities with an endogenous molecule (such as endorphin) and can bind to the same biological receptors.