General Chemistry Study Guide: Chemical Bonding, Chemical Formulas, Chemical Equations, and Aqueous Reactions

Chemical Bonding: Molecular Orbital Theory

Introduction to Molecular Orbital Theory

Molecular orbital (MO) theory is a model for chemical bonding that describes electrons in molecules as occupying molecular orbitals, which are formed from the combination of atomic orbitals. This theory helps explain the electronic structure, bond order, and magnetic properties of molecules.

• Chemical Bond (MO Theory): A chemical bond forms when atomic orbitals combine to create molecular orbitals that are occupied by electrons.

• Delocalized Orbitals: Electrons in delocalized orbitals are spread over several atoms, contributing to resonance and stability.

• Bond Order: Indicates the strength and stability of a bond; calculated as half the difference between the number of bonding and antibonding electrons.

• Paramagnetic vs. Diamagnetic: Paramagnetic molecules have unpaired electrons and are attracted to magnetic fields; diamagnetic molecules have all electrons paired and are repelled by magnetic fields.

Example: The bond order of O2 is 2, and it is paramagnetic due to two unpaired electrons in its molecular orbitals.

Key Equations

• $\text{Bond Order} = \frac{1}{2}(\text{Number of bonding electrons} - \text{Number of antibonding electrons})$

HTML Table: Comparison of Paramagnetic and Diamagnetic Substances

Property	Paramagnetic	Diamagnetic
Electron Configuration	Unpaired electrons	All electrons paired
Magnetic Behavior	Attracted to magnetic fields	Repelled by magnetic fields
Example	O2	N2

Chemical Formulas and Percent Composition

Formula Mass, Empirical and Molecular Formulas

Chemical formulas represent the composition of compounds. The formula mass is the sum of atomic masses in a chemical formula. Empirical formulas show the simplest whole-number ratio of elements, while molecular formulas show the actual number of atoms in a molecule.

• Formula Mass: The sum of the atomic masses of all atoms in a chemical formula.

• Percent Composition: The percentage by mass of each element in a compound.

• Empirical Formula: Simplest ratio of elements in a compound.

• Molecular Formula: Actual number of atoms of each element in a molecule.

Example: The empirical formula of hydrogen peroxide is HO; its molecular formula is H2O2.

Key Equations

• $\text{Percent Composition} = \frac{\text{Mass of element in 1 mol of compound}}{\text{Molar mass of compound}} \times 100\%$

HTML Table: Empirical vs. Molecular Formula

Type	Definition	Example
Empirical Formula	Simplest whole-number ratio	CH2O
Molecular Formula	Actual number of atoms	C6H12O6

Chemical Equations and Stoichiometry

Balancing Chemical Equations and Reaction Yields

Chemical equations represent chemical reactions, showing reactants and products. Balancing equations ensures the conservation of mass. Stoichiometry involves calculations based on balanced equations to determine quantities of reactants and products.

• Balancing Equations: Adjust coefficients to ensure equal numbers of each atom on both sides.

• Theoretical Yield: Maximum amount of product possible from given reactants.

• Actual Yield: Amount of product actually obtained.

• Percent Yield: Ratio of actual yield to theoretical yield, expressed as a percentage.

Example: In the reaction $2H_2 + O_2 \rightarrow 2H_2O$, two moles of hydrogen react with one mole of oxygen to produce two moles of water.

Key Equations

• $\text{Percent Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100\%$

HTML Table: Types of Reaction Yields

Type	Definition
Theoretical Yield	Maximum possible product
Actual Yield	Product obtained experimentally
Percent Yield	Actual/Theoretical × 100%

Aqueous Reactions and Solution Chemistry

Solutions, Concentration, and Types of Reactions

Aqueous reactions occur in water as the solvent. Solutions are homogeneous mixtures, and their concentration is commonly expressed in molarity. Types of reactions in solution include precipitation, acid-base, and oxidation-reduction reactions.

• Solution: Homogeneous mixture of solute dissolved in solvent.

• Molarity (M): Concentration unit defined as moles of solute per liter of solution.

• Precipitation Reaction: Formation of an insoluble product (precipitate) from soluble reactants.

• Acid-Base Reaction: Transfer of protons (H+) between reactants.

• Oxidation-Reduction (Redox) Reaction: Transfer of electrons between reactants.

Example: Mixing solutions of AgNO3 and NaCl produces a white precipitate of AgCl.

Key Equations

• $\text{Molarity} = \frac{\text{moles of solute}}{\text{liters of solution}}$

HTML Table: Types of Aqueous Reactions

Type	Description	Example
Precipitation	Formation of insoluble product	AgNO3 + NaCl → AgCl (s) + NaNO3
Acid-Base	Transfer of H+ ions	HCl + NaOH → NaCl + H2O
Redox	Transfer of electrons	Zn + CuSO4 → ZnSO4 + Cu

Important Vocabulary

• Molecular orbital (MO)

• Molecular orbital theory

• Bonding orbital

• Antibonding orbital

• MO diagram

• Bond order

• Formula mass

• Empirical formula

• Molecular formula

• Percent composition

• Chemical reaction

• Reactant

• Product

• Stoichiometry

• Theoretical yield

• Actual yield

• Percent yield

• Solution

• Solvent

• Solute

• Molarity

• Precipitate

• Electrolyte

• Strong/weak electrolyte

• Acid-base reaction

• Oxidation-reduction (redox) reaction

Additional info:

• These study notes are based on a set of homework and exam-style questions, vocabulary lists, and suggested textbook readings and problems, covering topics from chemical bonding (molecular orbital theory), chemical formulas and percent composition, chemical equations and stoichiometry, and aqueous reactions and solution chemistry.

• All topics are relevant to a General Chemistry college course, specifically chapters 9, 4, 7, and 8 as outlined in standard textbooks.