Atomic Structure and Chemical Bonding

Atomic Structure

• Atoms are the fundamental building blocks of matter.
• Atoms consist of a nucleus containing protons and neutrons, orbited by electrons.
• Protons have a positive charge, neutrons are neutral, and electrons have a negative charge.
• The number of protons defines the element.
• The number of protons plus neutrons gives the mass number of an atom.
• Atoms strive for a stable electron configuration, often through bonding.
• Isotopes are atoms of the same element with different numbers of neutrons.
• Atomic orbitals describe the probability of finding an electron in a specific region around the nucleus.

Chemical Bonding

• Chemical bonds hold atoms together in molecules and compounds.
• Ionic bonds form between metals and nonmetals through electron transfer.
• Covalent bonds form between nonmetals by sharing electrons.
• Metallic bonds occur within metals due to delocalized electrons.
• Hydrogen bonds are a special type of dipole-dipole interaction.
• Bond strength is related to the amount of energy required to break the bond.
• Bond polarity depends on the electronegativity difference between atoms.

Chemical Reactions

• Chemical reactions involve the rearrangement of atoms to form new substances.
• Reactants are the starting materials, products are the resulting substances.
• Chemical equations describe reactions, showing reactants and products with relative amounts.
• Stoichiometry relates the amounts of reactants and products in a balanced reaction.
• Reactions can be categorized by type (e.g., synthesis, decomposition, single replacement).
• Rates of reactions depend on factors like temperature, concentration, and surface area.
• Catalysts increase reaction rates without being consumed.

States of Matter

• Matter exists in solid, liquid, and gas states.
• Solids have a fixed volume and shape.
• Liquids have a fixed volume but take the shape of their container.
• Gases have neither a fixed volume nor shape.
• Phase transitions occur between states.
• Properties like density and temperature influence the state of matter.

Solutions

• Solutions are homogeneous mixtures of two or more substances.
• The solvent is the dissolving medium (usually liquid).
• The solute is the substance dissolved in the solvent.
• Concentration is the amount of solute in a given amount of solvent or solution.
• Solutions can be saturated, unsaturated, or supersaturated.
• Solubility is the maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature.
• Factors affecting solubility include temperature and pressure (especially for gases).

Acids and Bases

• Acids are substances that release hydrogen ions (H⁺) in solution.
• Bases are substances that release hydroxide ions (OH⁻) in solution.
• pH measures the acidity or basicity of a solution.
• The pH scale ranges from 0 to 14, with 7 being neutral.
• Acid-base reactions involve the transfer of protons.
• Strong acids and bases completely dissociate in water.
• Weak acids and bases only partially dissociate.

Thermodynamics

• Thermodynamics studies the energy changes in chemical and physical processes.
• First Law: Energy can be neither created nor destroyed, only transformed.
• Second Law: The total entropy of an isolated system can only increase over time.
• Enthalpy (ΔH) measures the heat absorbed or released during a reaction.
• Entropy (ΔS) measures the disorder or randomness of a system.
• Gibbs Free Energy (ΔG) determines if a reaction will occur spontaneously.

Kinetics

• Kinetics studies the rates of chemical reactions.
• Reaction rates depend on factors such as concentration, temperature, and catalysts.
• Collision theory explains how reactant particles must collide with sufficient energy and proper orientation to react.
• Activation energy is the minimum energy required for a reaction to occur.
• Reaction mechanisms describe the step-by-step process of a reaction.

Organic Chemistry

• Organic chemistry focuses on the study of carbon-containing compounds.
• Carbon forms four covalent bonds, exhibiting versatility.
• Hydrocarbons are the simplest organic compounds, consisting of hydrogen and carbon.
• Functional groups determine the chemical properties of organic molecules.
• Important classes of organic compounds include alcohols, aldehydes, ketones, carboxylic acids, amines, and amides.

Periodic Table

• The periodic table organizes elements based on their atomic number and properties.
• Elements are arranged in rows (periods) and columns (groups).
• Elements in the same group have similar chemical properties.
• The periodic table reveals trends in atomic radii, ionization energy, and electronegativity.
• Metals are typically on the left side of the table, nonmetals on the right, with metalloids in between.