Nuclear Chemistry

Types of Radiation

Nuclear chemistry involves the study of changes in atomic nuclei, including the emission of radiation. The three main types of radiation are alpha (α), beta (β), and gamma (γ) radiation.

• Alpha Radiation (α): Consists of helium nuclei (2 protons, 2 neutrons). Low penetration; stopped by paper.

• Beta Radiation (β): Consists of high-energy electrons. Moderate penetration; stopped by aluminum foil.

• Gamma Radiation (γ): Electromagnetic waves; high penetration; requires thick lead or concrete for shielding.

• Example: (alpha decay)

Writing Nuclear Reactions

Nuclear reactions are written by balancing mass numbers and atomic numbers.

• General Format:

• Example: (beta decay)

Measuring Radiation

Radiation is measured using units such as the becquerel (Bq), curie (Ci), and gray (Gy). Instruments like Geiger counters detect radiation levels.

• Becquerel (Bq): 1 disintegration per second.

• Curie (Ci): 3.7 × 1010 disintegrations per second.

• Gray (Gy): Absorbed dose of radiation.

Calculating Half-Life of a Radioisotope

The half-life is the time required for half of a radioactive sample to decay.

• Formula:

• Example: If = 10 years, after 20 years,

Medical Applications of Radioisotopes

Radioisotopes are used in medicine for diagnosis and treatment.

• Imaging: Technetium-99m in scans.

• Treatment: Iodine-131 for thyroid disorders.

Nuclear Fission vs. Nuclear Fusion

Nuclear fission and fusion are two types of nuclear reactions.

• Fission: Splitting of a heavy nucleus into smaller nuclei; used in nuclear reactors.

• Fusion: Combining of light nuclei to form a heavier nucleus; occurs in stars.

• Example (Fission):

• Example (Fusion):

Acids and Bases

Naming Acids and Bases

Acids and bases are named according to their composition.

• Acids: If the anion ends in -ide, use "hydro-...-ic acid"; if -ate, use "...ic acid"; if -ite, use "...ous acid".

• Bases: Named as "metal hydroxide" (e.g., sodium hydroxide).

• Example: HCl = hydrochloric acid; NaOH = sodium hydroxide

Bronsted-Lowry Definitions of Acids and Bases

The Bronsted-Lowry theory defines acids and bases based on proton transfer.

• Acid: Proton (H+) donor.

• Base: Proton (H+) acceptor.

• Example: NH3 + H2O → NH4+ + OH-

Strength of Acids and Bases

Acids and bases are classified as strong or weak based on their degree of ionization.

• Strong Acids: Completely ionize in water (e.g., HCl, HNO3).

• Weak Acids: Partially ionize (e.g., acetic acid).

• Strong Bases: Completely dissociate (e.g., NaOH).

• Weak Bases: Partially dissociate (e.g., NH3).

Acid-Base Equilibria

Acid-base reactions reach equilibrium, described by the equilibrium constant.

• Ka (acid dissociation constant):

• Kb (base dissociation constant):

Dissociation of Water

Water self-ionizes to form H+ and OH-.

• Equation:

• Kw (ion product constant): at 25°C

pH Scale & Calculations

The pH scale measures the acidity or basicity of a solution.

• Formula:

• pOH:

• Relationship:

• Example: If [H+] = 1 × 10-3 M, pH = 3

Acid-Base Reactions

Acids react with bases to form water and a salt.

• General Equation:

• Example: HCl + NaOH → NaCl + H2O

Titrations

Titration is a technique to determine the concentration of an acid or base.

• Process: A solution of known concentration is added to a solution of unknown concentration until the reaction is complete (equivalence point).

• Formula: (for monoprotic acids and bases)

Buffers

Buffers are solutions that resist changes in pH when small amounts of acid or base are added.

• Composition: Weak acid and its conjugate base, or weak base and its conjugate acid.

• Example: Acetic acid and sodium acetate.

• Buffer Equation: (Henderson-Hasselbalch equation)

Introduction to Organic Chemistry

Organic vs. Inorganic Compounds

Organic compounds contain carbon and are typically associated with living organisms, while inorganic compounds do not necessarily contain carbon.

• Organic: Carbon-based, often with hydrogen, oxygen, nitrogen, etc.

• Inorganic: Includes salts, metals, minerals.

• Example: CH4 (methane) is organic; NaCl (sodium chloride) is inorganic.

Alkanes – Formulas, Names, Drawings, Properties, Reactions

Alkanes are saturated hydrocarbons with only single bonds.

• General Formula:

• Naming: Prefix (number of carbons) + "-ane" (e.g., methane, ethane, propane).

• Properties: Nonpolar, low reactivity, used as fuels.

• Reactions: Combustion:

Alkanes with Substituents

Substituents are groups attached to the main carbon chain.

• Common Substituents: Alkyl groups (methyl, ethyl, etc.).

• Naming: Number the chain to give substituents the lowest possible numbers.

• Example: 2-methylpropane

Alkenes vs Alkynes

Alkenes and alkynes are unsaturated hydrocarbons with double and triple bonds, respectively.

• Alkenes: Contain at least one C=C double bond. General formula:

• Alkynes: Contain at least one C≡C triple bond. General formula:

• Example: Ethene (C2H4), Ethyne (C2H2)

Cis-Trans Isomers

Cis-trans isomerism occurs in alkenes due to restricted rotation around the double bond.

• Cis Isomer: Substituents on the same side of the double bond.

• Trans Isomer: Substituents on opposite sides.

• Example: cis-2-butene vs trans-2-butene

Addition Reactions of Alkenes

Alkenes undergo addition reactions, where atoms are added across the double bond.

• Hydrogenation: Addition of H2 to form alkanes.

• Halogenation: Addition of halogens (Cl2, Br2).

• Example:

Aromatic Compounds

Aromatic compounds contain benzene rings, characterized by stability and unique reactions.

• Benzene: C6H6, six-membered ring with alternating double bonds.

• Properties: Undergo substitution rather than addition reactions.

• Example: Toluene, phenol, aniline

Additional info: Academic context and examples were added to ensure completeness and clarity for exam preparation.