GOB Chemistry Study Notes: Matter, Atoms, Compounds, Organic Molecules, Reactions, and Intermolecular Forces

Ch. 1 Chemistry Basics - Matter and Measurement

Elements, Compounds, and Mixtures

• Element: A pure substance consisting of only one type of atom (e.g., O2, Fe).

• Compound: A substance formed from two or more elements chemically bonded in fixed ratios (e.g., H2O).

• Mixtures: Physical combinations of two or more substances. Homogeneous mixtures have uniform composition (e.g., saltwater), while heterogeneous mixtures do not (e.g., salad).

Elements: Symbols, Atomic Number, and Atomic Mass

• Chemical Symbol: One- or two-letter abbreviation for an element (e.g., Na for sodium).

• Atomic Number (Z): Number of protons in the nucleus; defines the element.

• Atomic Mass: Weighted average mass of an element's isotopes (in atomic mass units, amu).

• Isotopes: Atoms of the same element with different numbers of neutrons.

Physical vs. Chemical Change

• Physical Change: Alters form or appearance, not composition (e.g., melting ice).

• Chemical Change: Produces new substances (e.g., rusting iron).

Balancing Equations

• Ensures the same number of each atom on both sides of a chemical equation, reflecting the Law of Conservation of Mass.

Measurement and Units

• SI Units: Standard units for scientific measurement (mass: kg, volume: L, temperature: K).

• Metric Prefixes: kilo- (103), centi- (10-2), milli- (10-3), micro- (10-6), etc.

• Converting Units: Use conversion factors to switch between units (e.g., 1 in = 2.54 cm).

• Significant Figures: Reflect precision in measurements; rules for counting and rounding apply.

• Scientific Notation: Expresses numbers as a product of a coefficient and a power of ten (e.g., $6.02 \times 10^{23}$).

Common Units

• Mass: g, kg

• Volume: L, mL

• Density: $\text{Density} = \frac{\text{mass}}{\text{volume}}$

• Temperature: °C, K, °F

Example

• Convert 25.0 °C to Kelvin: $K = ^\circ C + 273.15 = 298.15\ K$

Ch. 2 Atoms and Radioactivity

Structure of the Atom

• Nucleus: Dense center containing protons and neutrons.

• Electron Cloud: Region around nucleus where electrons are likely found.

Atomic Number and Mass

• Atomic Number (Z): Number of protons.

• Atomic Mass (A): Number of protons + neutrons.

• Isotopes: Atoms with same Z but different A (e.g., 12C, 13C).

Ch. 3 Compounds - How Elements Combine

Electron Arrangement and the Octet Rule

• Electrons occupy energy levels (shells) around the nucleus.

• Octet Rule: Atoms tend to gain, lose, or share electrons to achieve 8 valence electrons (noble gas configuration).

Ionic and Covalent Compounds

• Ionic Compounds: Formed by transfer of electrons from metals to nonmetals; composed of cations (+) and anions (−).

• Covalent Compounds: Formed by sharing electrons between nonmetals.

• Lewis Structures: Diagrams showing valence electrons and bonding.

Balancing Ions and Naming

• Balance charges to write correct formulas (e.g., Na+ + Cl− → NaCl).

• Name cations first, then anions (e.g., calcium chloride).

Mole Concept

• Mole: Counting unit for atoms/molecules; $1\ \text{mol} = 6.022 \times 10^{23}$ particles (Avogadro's number).

• Molar Mass: Mass of 1 mole of a substance (g/mol).

VSEPR Theory and Molecular Shape

• VSEPR: Valence Shell Electron Pair Repulsion theory predicts molecular shapes based on electron pair repulsion.

Ch. 4 Introduction to Organic Compounds

Organic Molecules and Structures

• Organic compounds contain carbon and hydrogen, often with O, N, S, P, or halogens.

• Structures can be expanded, condensed, or skeletal (line-angle) formulas.

Nomenclature of Alkanes

• Alkanes: Saturated hydrocarbons with single bonds only.

• Prefix + -ane (e.g., methane, ethane, propane).

Functional Groups

• Groups of atoms that impart characteristic properties (e.g., alcohols, carboxylic acids).

Lipids

• Saturated: No double bonds (solid at room temp).

• Unsaturated: One or more double bonds (liquid at room temp); includes cis and trans isomers.

• Polysaturated: Multiple double bonds.

Isomerism

• Cis-trans Isomers: Same formula, different spatial arrangement around double bond.

• Chirality: Molecules with non-superimposable mirror images (chiral centers).

Ch. 5 Chemical Reactions

Types of Chemical Reactions

• Synthesis: Two or more substances combine to form one product.

• Decomposition: One substance breaks down into two or more products.

• Exchange (Single/Double Replacement): Atoms or ions are exchanged between compounds.

• Combustion: Substance reacts with O2, producing energy, CO2, and H2O.

• Reversible Reactions: Can proceed in both directions.

• Oxidation-Reduction (Redox): Electron transfer; oxidation = loss, reduction = gain of electrons.

• Hydrolysis: Splitting with water.

• Condensation: Joining with loss of water.

Reaction Energy and Kinetics

• Endothermic: Absorbs energy.

• Exothermic: Releases energy.

• Activation Energy: Minimum energy required for reaction to occur.

• Kinetics: Study of reaction rates.

Ch. 6 Carbohydrates - Life's Sweet Molecules

• Carbohydrates are reviewed in class; focus on structure, function, and isomerism (D/L forms).

Ch. 7 States of Matter and Their Attractive Forces

Attractive Forces

• Dispersion Forces: Weakest, present in all molecules due to temporary dipoles.

• Dipole-Dipole: Attraction between polar molecules.

• Hydrogen Bonding: Strong dipole-dipole interaction involving H bonded to N, O, or F.

• Ionic Attraction: Strongest, between oppositely charged ions.

Attractive Forces and Solubility

• Like dissolves like: Polar solutes dissolve in polar solvents; nonpolar in nonpolar.

• Amphipathic Compounds: Contain both hydrophilic and hydrophobic regions (e.g., surfactants, micelles, lipid bilayers).

Example Table: Types of Intermolecular Forces

Type of Force	Relative Strength	Example
Dispersion	Weakest	CH4
Dipole-Dipole	Intermediate	HCl
Hydrogen Bonding	Strong	H2O
Ionic Attraction	Strongest	NaCl

Additional info:

• Some content (e.g., page numbers, specific figures) referenced in the notes is omitted for clarity and generality.

• Further details on carbohydrates, acids/bases, proteins, nucleic acids, and metabolism are not included in these pages but are part of the GOB Chemistry curriculum.