Focus 2 Part 1: Chemical Bonds and Lewis Structures

Vocabulary practice flashcards covering ionic and covalent bonding, lattice energy, and Lewis structures from Focus 2 Part 1.

Octet Rule

The principle that main group atoms tend to form bonds to achieve a complete valence shell containing a maximum of 8 electrons ($2$ from the $s$ subshell plus $6$ from the $p$ subshell) to attain lower energy and greater stability.

Ionic Bond

A chemical bond formed between a metal and a non-metal through the transfer (losing and gaining) of electrons, held together by electrostatic attraction.

Covalent Bond

A chemical bond formed by the sharing of valence electrons between atoms, resulting in no positive or negative charges.

Electrostatic Attraction

The attraction between positive charges (cations) and negative charges (anions) that holds an ionic bond together and decreases the system's energy.

Salt

Another name for an ionic compound, characterized by a crystalline network where each ion is surrounded by multiple oppositely charged ions.

Formula Unit

The term used to describe a representative particle of an ionic compound (such as $NaCl$ or $CaCl_2$) because its ions exist in an extended crystal network rather than as discrete, separable molecules.

Shield Effect

The repulsion between inner electrons that protects outer electrons from the nuclear attraction force, causing main group elements to lose electrons from $p$ and $s$ subshells before $d$.

Sublimation

An endothermic phase change in which a substance transitions directly from a solid to a gas, such as solid sodium converting to sodium gas with an energy input of $108\,kJ$.

Bond Dissociation

An endothermic process requiring energy to break a covalent bond between atoms, such as breaking the bond in diatomic chlorine gas ($+122\,kJ$).

Lattice Energy

The energy released when positive and negative gaseous ions connect together to form an ionic solid network (for example, $787\,kJ$ released for $NaCl$).

Duplet

A stable valence shell containing a maximum of 2 electrons in the first shell ($1s$), applicable only to hydrogen and helium.

Melting Point

The temperature at which a solid begins melting into a liquid, which is typically very high for ionic compounds due to strong interionic attractions.

Central Atom

The middle atom in a Lewis structure, typically identified as the element with the lowest subscript in the formula (hydrogen can never serve as the central atom).

Terminal Atoms

The side or surrounding atoms attached to the central atom whose valence electron shells are completed first when drawing a Lewis structure.

Single Bond

A covalent connection represented by a single line, formed by sharing one pair of electrons between two atoms.

Double Bond

A covalent linkage formed when atoms share two pairs of electrons to fulfill their octets when insufficient valence electrons remain to complete the central atom with single bonds.

Triple Bond

A covalent linkage formed when two atoms share three pairs of electrons, seen in molecules such as $C_2H_2$ or the cyanide ion ($CN^-$).

Resonance

The condition in which a molecule or polyatomic ion (such as $NO_3^-$) has multiple valid Lewis structures that differ only in the positions of their double bonds.

Kekulé Structure

A structural representation of benzene showing alternating, moving double bonds that lack fixed positions between carbon atoms.