Chemistry: Chemical Bonding and Reaction Calculations

Comprehensive vocabulary flashcards covering fundamental chemistry concepts, molecular bonding, VSEPR geometries, intermolecular forces, reaction classifications, and stoichiometry calculations.

Atom

The smallest unit retaining an element's chemical identity (examples: $He$, $Na$).

Element

A pure substance containing only one type of atom (examples: $Fe$, $O_2$).

Molecule

A discrete group of covalently bonded atoms (examples: $O_2$, $H_2O$).

Compound

A pure substance composed of different elements chemically combined in a fixed ratio (examples: $H_2O$, $NaCl$).

Ion

An atom or group of atoms possessing a net electrical charge (examples: $Na^+$, $Cl^-$, $NH_4^+$).

Formula unit

The simplest whole-number ratio of ions in an ionic compound (example: $CaCl_2$).

Network covalent solids

Solids characterized by extensive covalent bonding throughout their structure with generally high melting points, such as diamond and $SiO_2$.

Organic compounds

Primarily carbon compounds, especially those containing $C-H$ bonds and their derivatives, such as $CH_4$, ethanol, and glucose.

Valence electrons

Electrons that participate in bonding, occupying the outermost principal energy level for main-group atoms.

Octet rule

The tendency of many main-group atoms to achieve eight surrounding electrons through gaining, losing, or sharing electrons.

Duplet rule

The electron-filling rule followed by hydrogen, where two electrons fill its first shell.

Ionic bond

The electrostatic attraction between oppositely charged ions, formed when electrons are transferred between atoms.

Covalent bond

A chemical bond formed by shared electron pairs, in which one shared pair represents two electrons.

Metallic bonding

Bonding resulting from positive metal cores attracting delocalized, mobile electrons, accounting for electrical conductivity, malleability, and ductility.

Electronegativity

A bonded atom's attraction for shared electrons, which generally increases across a period to the right and up a group.

Nonpolar covalent bond

A covalent bond featuring equal or nearly equal electron sharing, typically having an electronegativity difference ($\Delta EN$) of $0$ to $0.4$.

Polar covalent bond

A covalent bond with unequal electron sharing, typically occurring when the electronegativity difference ($\Delta EN$) is between approximately $0.5$ and $1.7$.

Formal charge

A bookkeeping tool assigning bonding electrons equally between bonded atoms, calculated as $FC = V - N - \frac{B}{2}$, where $V$ is valence electrons, $N$ is nonbonding electrons, and $B$ is bonding electrons.

Resonance hybrid

The true representation of a species with delocalized electron density, depicted by multiple resonance contributors with identical atom positions but different electron placements.

Sigma ($\sigma$) bond

A covalent bond formed by electron orbital overlap directly along the internuclear axis.

Pi ($\pi$) bond

A covalent bond formed by sideways overlap of parallel unhybridized $p$ orbitals, which restricts rotation.

VSEPR theory

Valence-Shell Electron-Pair Repulsion model, stating that electron domains arrange around a central atom to minimize electrostatic repulsion.

Electron geometry

The geometric arrangement of all electron domains around a central atom, including both bonding domains and nonbonding lone pairs.

Molecular geometry

The geometric arrangement describing only the relative positions of bonded atoms around a central atom.

Hybridization

A theoretical model that combines atomic orbitals mathematically into equivalent hybrid orbitals (such as $sp$, $sp^2$, or $sp^3$).

Steric number

The total count of sigma ($\sigma$) bonds plus central-atom lone pairs, used to determine orbital hybridization and domain geometry.

London dispersion forces

Intermolecular forces present in all atoms and molecules resulting from temporary electron fluctuations that induce instantaneous and induced dipoles.

Dipole-dipole forces

Electrostatic attractions between the permanent dipoles of polar molecules.

Hydrogen bonding

A strong dipole attraction occurring when a hydrogen atom covalently bonded to $N$, $O$, or $F$ interacts with an electronegative atom's lone pair.

Ion-dipole force

An intermolecular interaction where an ion attracts the oppositely charged end of a polar molecule, such as water surrounding dissolved $Na^+$ and $Cl^-$ ions.

Synthesis reaction

A chemical reaction in which two or more reactants combine to form a single product, following the general pattern $A + B \rightarrow AB$.

Decomposition reaction

A reaction where a single reactant breaks down into two or more products, often driven by heat, light, or electricity ($AB \rightarrow A + B$).

Single replacement reaction

A reaction in which a free element displaces another element from a compound ($A + BC \rightarrow AC + B$), governed by the activity series.

Double replacement reaction

A metathesis reaction where two compounds exchange ionic partners ($AB + CD \rightarrow AD + CB$), occurring when an insoluble precipitate, gas, or weak electrolyte forms.

Combustion reaction

A rapid reaction between a substance and oxygen; complete combustion of a hydrocarbon yields $CO_2$ and $H_2O$.

Acid-base neutralization

A reaction where an acid transfers a proton ($H^+$) to a base, commonly forming water and a salt.

Spectator ions

Ions that remain dissolved and unchanged on both reactant and product sides of a reaction and are eliminated to form the net ionic equation.

Net ionic equation

A chemical equation displaying only the participating species that undergo a chemical change, omitting spectator ions.

Mole

The SI base unit containing exactly $6.02214076 \times 10^{23}$ specified elementary particles (atoms, molecules, ions, or formula units).

Molar mass

The mass in grams of one mole of a chemical substance, expressed in $g\,mol^{-1}$.

Limiting reactant

The reactant that is completely consumed first in a chemical reaction according to stoichiometric proportions, limiting the maximum product formed.

Excess reactant

The reactant remaining unconsumed after the limiting reactant has been completely transformed into products.

Theoretical yield

The calculated maximum amount of product that can form from a given amount of limiting reactant, assuming complete and ideal conversion.

Actual yield

The measurable quantity of product obtained experimentally from a chemical reaction in the laboratory.

Percent yield

The ratio of the actual yield to theoretical yield expressed as a percentage: $\left(\frac{\text{actual yield}}{\text{theoretical yield}}\right) \times 100$.