Chemical Bonding and Oxy-acid Vocabulary Flashcards

This set of vocabulary flashcards defines the essential principles of chemical bonding, octet rule variations, hybridization, and the nomenclature of complex acids found in the lecture notes.

Octet Rule

The tendency of atoms to acquire an octet ($ns^2np^6$) configuration or to attain the nearest noble gas configuration in their outermost orbit to achieve stability.

Hypovalent Compounds

Chemical species, such as $BeF_2$, $BF_3$, and $AlCl_3$, where the central atom has an incomplete octet with fewer than 8 electrons in its valence shell.

Hypervalent Compounds

Chemical species where the central atom, such as in $PCl_5$ (10e) or $SF_6$ (12e), expands its octet to accommodate more than 8 electrons, often due to available empty d-orbitals.

Pseudo inert gas configuration

An electronic configuration represented as $(ns^2np^6nd^{10})$, found in transition metal ions like $Zn^{2+}$ and $Cd^{2+}$.

Ionic (Electrovalent) Bond

A non-directional chemical bond formed between atoms as a result of the complete transfer of one or more electrons from one atom to another.

Covalent Bond

A directional chemical bond formed by the mutual sharing of electrons between two atoms with opposite spins.

Covalency

The capacity of an atom to form covalent bonds, represented by small lines (e.g., single, double, or triple bonds).

Bond Length

The internuclear distance between two atoms at the point of minimum potential energy, such as $74\text{ pm}$ for the $H_2$ molecule.

Bond Dissociation Energy (B.D.E.)

The amount of energy released when one mole of a specific bond type is formed, or the energy required to dissociate it, such as $434.2\text{ kJ }mol^{-1}$ for $H_2$.

Orbital Overlap Concept

The partial merging or interpenetration of atomic orbitals that results in the pairing of electrons and determines the strength of a covalent bond.

Sigma ($\sigma$) Bond

A strong covalent bond formed by the end-to-head (head-on) overlap of bonding orbitals along the internuclear axis.

Pi ($\pi$) Bond

A covalent bond formed by sidewise or lateral overlapping of atomic orbitals where their axes remain parallel to each other and perpendicular to the internuclear axis.

Delta ($\delta$) Bond

Covalent bonds formed where four lobes of a d-orbital of one atom overlap with four lobes of a similar d-orbital of another atom.

Hybridisation

The phenomenon of intermixing atomic orbitals of slightly different energies to redistribute their energies, resulting in a new set of equivalent orbitals in energy and shape.

Steric Number (S.N.)

A value used to determine hybridization calculated as the number of $\sigma$-bonds around an atom plus the number of lone pairs on that atom.

Oxy-acids

Compounds containing an $X-O-H$ bond where $X$ is typically a non-metal; these are essentially aqueous solutions of acidic oxides.

Basicity

The number of hydrogen atoms attached directly to oxygen in an oxy-acid that are acidic in nature and can ionize in solution.

Pyro Acid

An oxy-acid formed by the removal of one mole of $H_2O$ from two moles of a parent oxy-acid, usually containing an $X-O-X$ bond.

Hypo Acid

An oxy-acid obtained by removing one oxygen atom from the '-ous' form of the parent acid.

Peroxy Acid

Oxy-acids that contain a peroxy linkage ($O-O$) and are obtained by adding one oxygen to the '-ic' form of the acid while maintaining the central atom's oxidation state.

Thio Acid

Oxy-acids in which one or more oxygen atoms are replaced by sulfur atoms, or those containing $S-S$ bonds.

Resonance

The phenomenon where multiple structures (canonical or resonating structures) are used to represent a single molecule that cannot be fully described by one structure alone.

Formal Charge (F.C.)

A charge assigned to an atom in a molecule calculated using the formula: $\text{Valence } e^- - \text{Dots (lone electrons)} - \text{Lines (bonds)}$.