Ch 2: Chemical Bonds and Reactions

Vocabulary flashcards covering atomic structure, isotopes, covalent and non-covalent chemical bonds, ionic interactions, and chemical reactions from the lecture notes.

Isotope

Two atoms of an element that differ in their number of neutrons while having the same number of protons.

Radioactive Isotopes

Isotopes that decay spontaneously, giving off particles and energy; used in research to date fossils, trace atoms through metabolic processes, and diagnose medical disorders.

Valence Shell

The outermost electron shell of an atom.

Valence Electrons

Electrons located in the outermost shell (valence shell) that mostly determine the chemical behavior of an element.

Chemically Inert Elements

Elements that have a full valence shell and are chemically unreactive, such as noble gases.

Covalent Bonds

Chemical bonds formed when atoms share valence shell electrons to complete their valence shells.

Electronegativity

An atom's attraction for the electrons in a covalent bond, based on the atom’s number of protons (more protons, stronger pull) and the valence shell’s distance from the nucleus (shorter distance, stronger pull).

Nonpolar Covalent Bond

A covalent bond in which the participating atoms share the electrons equally.

Polar Covalent Bond

A covalent bond where one atom is more electronegative than the other, resulting in unequal electron sharing and partial positive ($\delta+$) or negative ($\delta-$) charges on each atom.

Ion

A charged atom or molecule.

Cation

A positively charged ion ($+\text{charge}$).

Anion

A negatively charged ion ($-\text{charge}$).

Ionic Bond

The electrostatic attraction between an anion and a cation formed when one atom strips electrons from its bonding partner; typically covalent in the dry state and non-covalent in solution.

Salts

Compounds formed by ionic bonds consisting of a rigid system of ion bonds.

Non-Covalent Bonds

Weak chemical bonds essential in biological structures, including ionic bonds in solution, hydrogen bonds, van der Waals interactions, and hydrophobic interactions.

Hydrogen Bond

A weak interaction formed when a hydrogen atom covalently bound to one electronegative atom is also attracted to another electronegative atom (typically $\text{O}$ or $\text{N}$ in living cells).

H-Bond Donor

The electronegative atom to which a hydrogen atom is covalently bound in a hydrogen bonding pair.

H-Bond Acceptor

The electronegative atom that electrostatically attracts the partially positive hydrogen atom in a hydrogen bond.

Van Der Waals Interactions

Attractions between molecules that are close together (steric fit) created by asymmetrical electron distribution that produces transient hot spots of positive or negative charge.

Hydrophobic Interactions

Also called non-polar interactions; occurrences where non-polar molecules stick together as they try to exclude or get away from water ($\text{H}_2\text{O}$).

Chemical Reactions

Processes that make and break chemical bonds.

Reactants

The starting molecules in a chemical reaction.

Products

The final molecules resulting from a chemical reaction.

Photosynthesis Reaction

An important biological chemical reaction described by the equation $6\text{CO}_2 + 6\text{H}_2\text{O} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$.

Chemical Equilibrium

The state reached when the forward and reverse reaction rates are equal, causing the concentrations of reactants and products to remain constant (though rarely equal).