Key Concepts in Chemical Bonding and Molecular Structure

Lewis Dot Diagrams

Visual representation of valence electrons in molecules.

Octet Rule

Atoms prefer to have eight electrons in valence shell.

Ionization Energy

Energy required to remove an electron from an atom.

Diatomic Elements

Molecules consisting of two atoms, e.g., O2.

Electronegativity

Ability of an atom to attract electrons in a bond.

Atomic Radius

Distance from nucleus to outermost electron shell.

Electron Affinity

Energy change when an electron is added to an atom.

Formal Charge Calculation

Valence electrons minus assigned electrons.

Ionic Bonds

Electrons transferred between metals and nonmetals.

Covalent Bonds

Electrons shared between nonmetal atoms.

Polarity

Distribution of electron density in a molecule.

Isomers

Compounds with same formula but different arrangements.

Moles

Unit measuring amount of substance, 6.02 x 10^23 particles.

Mass Spectroscopy

Technique to determine mass of isotopes in elements.

Empirical Formula

Simplest ratio of elements in a compound.

Coulomb's Law

Force between charges inversely proportional to distance squared.

Resonance

Molecule represented by multiple valid Lewis structures.

Bond Energy

Energy required to break a chemical bond.

Potential Energy Diagrams

Graphs showing energy changes during bond formation.

Reactivity Trends

Metal reactivity increases down a group; nonmetals vary.

Allotropes

Different structural forms of the same element.

% Composition

Mass of part divided by mass of whole times 100.

% Error

Difference between measured and accepted values.

Stable Isotopes

Atoms with equal protons and neutrons, non-radioactive.

Triple Bonds

Bond involving three shared pairs of electrons.

Hybridization

Mixing atomic orbitals to create hybrid orbitals.

sp Hybridization

Linear shape, bond angle 180° (e.g., BeCl₂).

sp² Hybridization

Trigonal planar shape, bond angle 120° (e.g., BF₃).

sp³ Hybridization

Tetrahedral shape, bond angle 109.5° (e.g., CH₄).

Molecular Polarity

Determined by symmetry and net dipole moment.

Sigma Bonds

Single bonds formed by end-to-end orbital overlap.

Pi Bonds

Double/triple bonds formed by side-to-side overlap.

Alloys

Mixtures of metals or metals with nonmetals.

Percent Composition

Mass percentage of each element in a compound.

Impurities

Unwanted substances affecting sample purity.

Intermolecular Forces

Forces between molecules affecting physical properties.

London Dispersion Forces

Weak forces due to temporary dipoles.

Dipole-Dipole Interactions

Attraction between polar molecules' positive and negative ends.

Hydrogen Bonds

Strong dipole-dipole interactions involving H and electronegative atoms.

Formal Charges

Help determine the most stable Lewis structure.

Bond Orders

Number of bonds between two atoms.

Atomic Masses for Isotopes

Specific mass and abundance for each isotope.

Average Atomic Mass

Calculated from isotope mass and abundance.

Conversions

Grams to moles and moles to liters at STP.

Purity of an Element

Degree of substance free from contaminants.