Chemical Bonding and Geometry

Flashcards covering the fundamentals of chemical bonding, nomenclature, Lewis structures, and molecular geometry based on the lecture transcript.

Ionic Bonds

Bonds formed by the complete transfer of electrons typically between metals and non-metals.

Crystal Lattices

Structures in which ionic compounds form where ions are held together by strong electrostatic forces of attraction in a repetitive pattern.

Inert Pair Effect

The tendency of the $s$-electron pair to remain unionized in heavier elements like $Tl$, $Sn$, $Pb$, and $Bi$, leading to a valency 2 lower than the expected group valency.

Bond Length

The internuclear distance at which the lowest potential energy is achieved between two atoms.

Electronegativity

The ability of an atom to attract a pair of electrons in a chemical bond, typically calculated on a scale ranging from 0 to 4.

Pure Covalent Bonds

Bonds in which the electrons are shared equally between atoms, such as in a diatomic molecule with two identical atoms.

Polar Covalent Bonds

Bonds in which the electrons are shared unequally because one atom exerts a stronger force of attraction due to higher electronegativity.

Electron Affinity

A measurable physical quantity representing the energy released or absorbed (measured in $kJ/mol$) when an isolated gas-phase atom acquires an electron.

Binary Compounds

Chemical compounds composed of two different elements, which can be either ionic (metal-nonmetal) or covalent (nonmetal-nonmetal).

Polyatomic Ions

Ions that contain more than one atom, such as ammonium ($NH_4^+$) or sulfate ($SO_4^{2-}$).

Hydrates

Ionic compounds that contain weakly bound water molecules as part of their crystals, such as copper(II) sulfate pentahydrate ($CuSO_4 \times 5H_2O$).

Binary Acids

Acids comprised of hydrogen and one other nonmetallic element, named with the prefix hydro- and the suffix -ic.

Oxyacids

Acids that contain oxygen atoms where the name suffix changes from -ate to -ic or -ite to -ous.

Lewis Symbol

An elemental symbol surrounded by one dot for each of its valence electrons.

Octet Rule

The tendency of main group elements to form enough bonds to obtain eight valence electrons.

Lone Pairs

Electrons not involved in bonding that are drawn on the outside of each atom in a Lewis structure.

Free Radicals

Odd-electron molecules that have an odd number of valence electrons and therefore possess an unpaired electron.

Hypervalent Molecules

Molecules formed from elements in the third and higher periods ($n \text{ } \boldsymbol{\beta} \text{ } 3$) that can share more than four pairs of electrons by using empty $d$ orbitals.

Formal Charge (FC)

The hypothetical charge of an atom in a molecule calculated as $FC = \text{\# valence shell electrons} - \text{\# lone pair electrons} - \frac{1}{2} \text{\# bonding electrons}$.

Resonance Hybrid

The average of several possible resonance forms for a molecule or ion where the actual distribution of electrons is an average of the Lewis structures.

VSEPR Theory

Valence Shell Electron Pair Repulsion model which assumes that valence shell electron pairs (bonding and nonbonding) spread out to minimize repulsions.

Electron-pair Geometry

The 3-D arrangement of all electron domains (bond pairs and lone pairs) around a central atom.

Molecular Structure

The actual arrangement of atoms around a central atom, which may differ from electron-pair geometry if lone pairs are present.

Bond Dipole Moment

A vector quantity representing the separation of charge in a molecule, defined by the magnitude of partial charges ($Q$) and the distance between them ($r$), given by $\boldsymbol{\beta} = Q \times r$.