GOB Chemistry Study Guide: Organic Compounds, Chemical Reactions, Carbohydrates, and Gas Laws

Chapter 4: Introduction to Organic Compounds

Representations of Molecules

Organic molecules can be represented in several ways, each providing different levels of structural detail.

• Molecular Formula: Shows the number and type of atoms (e.g., C2H6).

• Condensed Formula: Groups atoms to show connectivity (e.g., CH3CH3).

• Lewis/Expanded Formula: Shows all atoms and bonds, including lone pairs.

• Skeletal Formula: Simplifies carbon backbone; vertices represent carbon atoms, hydrogens often omitted.

Example: Ethanol can be written as C2H6O (molecular), CH3CH2OH (condensed), or as a skeletal structure.

Functional Group Identification

Functional groups are specific atom arrangements that define chemical properties and reactivity.

• Alkanes: Only single bonds (C–C).

• Alkenes: At least one double bond (C=C).

• Alkynes: At least one triple bond (C≡C).

• Alcohol: Contains –OH group.

• Amine: Contains –NH2, –NHR, or –NR2.

• Ether: Contains C–O–C linkage.

• Alkyl Halide: Contains halogen (F, Cl, Br, I) attached to carbon.

• Aromatic: Contains benzene ring.

• Amide: Contains –CONH2 group.

• Carboxylic Acid: Contains –COOH group.

• Aldehyde: Contains –CHO group.

• Ketone: Contains C=O within carbon chain.

• Ester: Contains –COOR group.

Additional info: Thiols (–SH), sulfides (C–S–C), disulfides (–S–S–), and phenols (aromatic –OH) are also important functional groups.

IUPAC Naming of Organic Compounds

The International Union of Pure and Applied Chemistry (IUPAC) system provides rules for naming organic molecules.

• Alkanes: Name based on longest carbon chain; add "-ane" suffix.

• Alkenes: Use "-ene" suffix; indicate position of double bond.

• Alkynes: Use "-yne" suffix; indicate position of triple bond.

• Alcohols: Use "-ol" suffix; number to show position of –OH.

• Alkyl Halides: Prefix (chloro-, bromo-, etc.) for halogen substituents.

• Ketones: Use "-one" suffix; number to show position of C=O.

• Carboxylic Acids: Use "-oic acid" suffix.

• Aldehydes: Use "-al" suffix.

Example: 2-bromopropane, 3-pentanol, ethanoic acid.

Bond Length vs. Bond Strength

Bond length and strength are inversely related; shorter bonds are stronger.

• Single bonds: Longest and weakest.

• Double bonds: Shorter and stronger than single bonds.

• Triple bonds: Shortest and strongest.

Example: C–C (single) > C=C (double) > C≡C (triple) in strength.

Substituent Naming

Substituents are groups attached to the main carbon chain.

• Alkyl: Methyl (CH3–), ethyl (CH3CH2–), propyl, etc.

• Halogen: Chloro (Cl), bromo (Br), fluoro (F), iodo (I).

Isomers

Isomers are compounds with the same formula but different structures.

• Structural Isomers: Differ in connectivity.

• Stereoisomers: Same connectivity, different spatial arrangement.

Stereoisomers: Cis/Trans and Chirality

Stereoisomers include cis/trans and chiral molecules.

• Cis/Trans: Cis = same side; trans = opposite side (applies to double bonds and cyclic structures).

• Chiral Center: Carbon with four different groups; molecule is chiral if it has at least one chiral center.

• Enantiomers: Non-superimposable mirror images.

Example: 2-butanol has a chiral center; cis-2-butene vs. trans-2-butene.

Fatty Acid Nomenclature

Fatty acids are classified by saturation and double bond position.

• Omega designation: Position of double bond from methyl end (omega).

• X:X designation: Number of carbons:number of double bonds (e.g., 18:1).

• Saturated: No double bonds.

• Monounsaturated: One double bond.

• Polyunsaturated: Multiple double bonds.

Chapter 5: Chemical Reactions

Enthalpy (ΔH) and Free Energy (ΔG)

Thermodynamics describes energy changes in reactions.

• Enthalpy (ΔH): Heat change; exothermic (ΔH < 0), endothermic (ΔH > 0).

• Free Energy (ΔG): Determines spontaneity; exergonic (ΔG < 0, spontaneous), endergonic (ΔG > 0, non-spontaneous).

Equation:

$\Delta G = \Delta H - T \Delta S$

Factors Affecting Reaction Rate

Reaction rates can be increased by:

• Increasing temperature

• Increasing concentration of reactants

• Adding a catalyst

Categories of Organic Reactions

Organic reactions are classified by how bonds are made or broken.

• Synthesis: Two or more reactants form one product.

• Decomposition: One reactant breaks into two or more products.

• Exchange/Displacement: Parts of molecules are swapped.

Specific Types of Reactions

• Redox (Inorganic and Organic): Electron transfer; oxidation (loss), reduction (gain).

• Combustion: Reaction with O2 producing CO2 and H2O.

• Addition: Atoms added to double/triple bonds (hydration, hydrogenation).

• Condensation: Two molecules join, releasing water.

• Hydrolysis: Water splits a molecule.

Example: Hydration of alkene: $CH_2=CH_2 + H_2O \rightarrow CH_3CH_2OH$

Chapter 6: Carbohydrates – Life's Sweet Molecules

Classification of Carbohydrates

Carbohydrates are classified by size and complexity.

• Monosaccharides: Single sugar units (glucose).

• Disaccharides: Two monosaccharides joined (sucrose).

• Oligosaccharides: 3–10 sugar units.

• Polysaccharides: Many sugar units (starch, cellulose).

Alcohol Classification in Carbohydrates

Alcohols are classified by the number of carbons attached to the –OH bearing carbon.

• Primary: –OH on carbon attached to one other carbon.

• Secondary: –OH on carbon attached to two other carbons.

• Tertiary: –OH on carbon attached to three other carbons.

Monosaccharide Types

Monosaccharides are named by carbon number and functional group.

• Triose: 3 carbons

• Tetrose: 4 carbons

• Pentose: 5 carbons

• Hexose: 6 carbons

• Aldose: Aldehyde group

• Ketose: Ketone group

Stereochemistry of Monosaccharides

Monosaccharides can have multiple stereoisomers.

• Diastereomers: Not mirror images, differ at some chiral centers.

• Enantiomers: Mirror images, differ at all chiral centers.

• Epimers: Differ at only one chiral center.

Anomeric Carbon and Cyclic Forms

Monosaccharides cyclize to form hemiacetals.

• Anomeric Carbon: C1 in aldoses; forms bond with –OH.

• Alpha: –OH down (on anomeric carbon).

• Beta: –OH up.

Example: Glucose forms alpha and beta cyclic forms.

Reducing Sugars

Reducing sugars have free anomeric –OH or aldehyde group.

• Monosaccharides are reducing sugars.

• Disaccharides are reducing if anomeric carbon is free.

Formation of Disaccharides

Two monosaccharides join via condensation to form glycosidic bonds.

• Alpha or Beta: Depends on orientation of anomeric –OH.

• Numbering: Indicates which carbons are linked (e.g., 1→4).

Example: Maltose: alpha-1,4-glycosidic bond.

Polysaccharides: Storage and Structure

Polysaccharides serve as energy storage or structural materials.

• Storage: Starch (plants: amylose + amylopectin), glycogen (animals).

• Structure: Cellulose (plants), chitin (fungi/insects).

Bonding and Structure of Polysaccharides

• Amylose: Linear, alpha-1,4 bonds.

• Amylopectin: Branched, alpha-1,4 and alpha-1,6 bonds.

• Cellulose: Linear, beta-1,4 bonds.

• Chitin: Similar to cellulose, contains N-acetylglucosamine.

• Glycogen: Highly branched, alpha-1,4 and alpha-1,6 bonds.

ABO Blood Typing and Oligosaccharides

Blood types are determined by oligosaccharide antigens.

• Universal donor: Type O (no antigen).

• Universal acceptor: Type AB (both antigens).

Heparin

Heparin is a polysaccharide used as an anticoagulant.

• Prevents blood clotting.

Chapter 7.1: States of Matter and Their Attractive Forces – Gas Laws

Pressure Unit Conversion

Pressure can be measured in several units; conversion factors are essential.

• Common units: atm, mmHg (torr), Pa, psi.

• 1 atm = 760 mmHg = 101,325 Pa = 14.7 psi

Boyle’s Law (Conceptual)

Boyle’s Law describes the relationship between pressure and volume at constant temperature.

• As volume decreases, pressure increases (inverse relationship).

Equation:

$P_1 V_1 = P_2 V_2$

Charles’ Law (Conceptual)

Charles’ Law describes the relationship between volume and temperature at constant pressure.

• As temperature increases, volume increases (direct relationship).

Equation:

$\frac{V_1}{T_1} = \frac{V_2}{T_2}$

Gay-Lussac’s Law (Conceptual)

Gay-Lussac’s Law describes the relationship between pressure and temperature at constant volume.

• As temperature increases, pressure increases (direct relationship).

Equation:

$\frac{P_1}{T_1} = \frac{P_2}{T_2}$

Extra Credit: Calculations Using Gas Laws

Use the provided equations to solve for unknown variables when other values are given.

Law	Variables	Equation
Boyle's Law	Pressure, Volume	$P_1 V_1 = P_2 V_2$
Charles' Law	Volume, Temperature	$\frac{V_1}{T_1} = \frac{V_2}{T_2}$
Gay-Lussac's Law	Pressure, Temperature	$\frac{P_1}{T_1} = \frac{P_2}{T_2}$