Introduction to Chemistry: Key Concepts and Principles
Chemical Reactions
Four observations suggesting a chemical reaction:
- Evolution of energy as heat and light
- Production of gas
- Change in color
- Formation of a precipitate
Balanced Chemical Equations:
Represent the identities and relative amounts of reactants and products using symbols and formulas.
Kinetic-Molecular Theory
States of Matter
Explains the properties of gases, liquids, and solids.
Gases
- Describes a model of an ideal gas.
- Gases consist of numerous tiny, fast-moving particles far apart relative to their size.
Solids
Crystalline Solids:
Possess a total three-dimensional array of points describing the arrangement of particles.
Amorphous Solids:
Lack a highly ordered structure or regular shape, unlike crystalline solids.
Phase Transitions
Molar Enthalpy of Fusion:
The energy as heat required to melt one mole of solid at its melting point.
Equilibrium:
A dynamic condition with two opposing changes occurring at equal rates in a closed system.
Equilibrium Vapor Pressure:
The pressure exerted by a vapor in equilibrium with its liquid at a given temperature.
Gas Laws
Gay-Lussac’s Law of Combining Volumes:
Volumes of reacting gases and products at the same temperature and pressure can be expressed as ratios of whole numbers.
Avogadro’s Law:
Equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.
Dalton’s Law of Partial Pressures:
In a mixture of non-reacting gases, the total pressure equals the sum of the partial pressures of each gas.
Graham’s Law of Effusion:
Relative rates of effusion of gases at the same temperature and pressure are inversely proportional to the square roots of their molar masses.
Acids and Bases
Properties of Acids:
- Sour taste
- React with active metals
- Change colors of acid-base indicators
- React with bases to produce salts and water
- Conduct electricity in aqueous solutions
Properties of Bases:
- Bitter taste
- Slippery feel in dilute aqueous solutions
- Change colors of acid-base indicators
- React with acids to produce salts and water
- Conduct electricity in aqueous solutions
Acid-Base Theories
Arrhenius Theory:
- Acids contain hydrogen and ionize in water to form hydrogen ions.
- Bases produce hydroxide ions in aqueous solutions.
Brønsted-Lowry Theory:
- Acids are proton donors.
- Bases are proton acceptors.
Lewis Theory:
- Acids are electron-pair acceptors.
- Bases are electron-pair donors.
Acid Strength and Reactions
Acid Classification:
Described as monoprotic, diprotic, or triprotic based on the number of protons they can donate.
Conjugate Acid-Base Pairs:
Every Brønsted-Lowry acid-base reaction has two conjugate acid-base pairs.
Acid-Base Strength:
- Strong acids have weak conjugate bases.
- Strong bases have weak conjugate acids.
Proton-Transfer Reactions:
Favor the production of the weaker acid and weaker base.
Neutralization Reactions:
Produce water and a salt (ionic compound).
pH and Titration
pH Measurement:
Measured using a pH meter or acid-base indicators.
Titration:
Uses a solution of known concentration to determine the concentration of an unknown solution.
Organic Chemistry
Carbon Compounds
Carbon’s Versatility:
Ability to bond with other elements and form diverse arrangements contributes to the variety of carbon compounds.
Isomers:
- Compounds with the same molecular formula but different structures.
- Structural isomers: Atoms bonded in different orders.
- Geometric isomers: Same atom bonding order but different spatial orientation.
Hydrocarbons
Alkanes:
- Saturated hydrocarbons containing only single bonds.
- Physical trends correspond to size and branching.
Unsaturated Hydrocarbons:
- Have one or more multiple carbon-carbon bonds.
- Include alkenes, alkynes, and aromatic hydrocarbons.
Functional Groups
Functional Group Influence:
Responsible for the properties of the organic compound containing them.
Common Functional Groups:
- Alcohols: Contain the hydroxyl group (-OH).
- Alkyl halides: Contain one or more halogen atoms.
- Ethers: Two alkyl groups joined to an oxygen atom.
- Aldehydes and Ketones: Contain the carbonyl group (C=O).
- Amines: Derivatives of ammonia.
- Carboxylic acids: Contain carboxyl groups (-COOH).
- Esters: Carboxylic acid’s hydrogen replaced with an alkyl group.
Polymers
Polymer Structure:
- Large molecules made of repeating units called monomers.
- Copolymers: Consist of two or more different monomers.
Biochemistry
Carbohydrates
Carbohydrate Composition:
Nutrients produced by plants, made of carbon, oxygen, and hydrogen.
Carbohydrate Types:
- Monosaccharides: Simplest carbohydrates.
- Disaccharides: Two monosaccharides joined together.
- Polysaccharides: More than two monosaccharides joined together.
Carbohydrate Reactions:
Undergo condensation and hydrolysis reactions.
Lipids
Lipid Characteristics:
Diverse group of biochemical molecules with a high percentage of carbon and hydrogen atoms.
Proteins
Amino Acids:
Basic building blocks of proteins.
Protein Structure:
- Biological polymers with a unique sequence of amino acid monomers.
- Function related to shape.
- Side-chain interactions result in secondary, tertiary, and quaternary structures.
Energy and Metabolism
ATP:
High-energy storage compound used for storing and providing energy.
Metabolic Pathways:
- Involve ATP to ADP and ADP to ATP conversions.
- Classified as catabolism and anabolism.
Catabolism:
Breakdown of large molecules into simpler ones, releasing energy.
Anabolism:
Energy-consuming pathways for producing molecules needed for growth and repair.
Nucleic Acids
DNA and RNA:
Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are nucleic acids essential for reproduction.
Nucleic Acid Structure:
Polymers of monomer units called nucleotides.
DNA Structure:
- Double helix with two complementary strands.
- Strands held together by hydrogen bonding of base pairs.
RNA Function:
Used to produce proteins in the cell.