Atomic Structure and Chemical Bonding

Atomic Structure

• Atoms are the fundamental building blocks of matter, composed of a nucleus containing protons and neutrons, surrounded by electrons.
• Protons carry a positive charge, electrons carry a negative charge, and neutrons are neutral.
• The number of protons in an atom defines its atomic number and determines the element.
• Atomic mass is approximately the sum of protons and neutrons.
• Isotopes are atoms of the same element with different numbers of neutrons.
• Electron arrangement within shells and orbitals dictates chemical properties.
• Quantum numbers describe the energy level, shape, and orientation of atomic orbitals.

Chemical Bonding

• Atoms bond to achieve a stable electron configuration, often a filled outermost electron shell.
• Ionic bonds form between ions with opposite charges, held together by electrostatic attraction.
• Covalent bonds form when atoms share electrons.
• Metallic bonds result from the sharing of delocalized electrons among many atoms.
• Polar covalent bonds occur when electrons are shared unequally, leading to a dipole moment.
• Hydrogen bonding is a specific type of dipole-dipole interaction between a hydrogen atom bonded to a highly electronegative atom (e.g., oxygen, nitrogen, fluorine) and another electronegative atom.

States of Matter

• Matter exists in three primary states: solid, liquid, and gas.
• 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 involve changes between these states, including melting, freezing, vaporization, condensation, and sublimation.
• The kinetic energy of the particles is related to the temperature of the material.
• Intermolecular forces are crucial in determining the properties of liquids and solids.

Chemical Reactions

• Chemical reactions involve the rearrangement of atoms to form new substances.
• Reactants are the substances that undergo change, while products are the newly formed substances.
• Chemical equations represent these changes, showing reactants and products separated by an arrow.
• Balancing chemical equations ensures conservation of mass.
• Reaction rates are influenced by factors like temperature, concentration, surface area, and catalysts.
• Different reaction types include synthesis, decomposition, single displacement, double displacement, combustion, and acid-base reactions.

Solutions

• Solutions are homogeneous mixtures of two or more substances, composed of a solute dissolved in a solvent.
• Concentration expresses the amount of solute in a given amount of solvent or solution.
• Factors like temperature and pressure affect solubility.
• Colligative properties depend on the concentration of solute particles rather than the identity of the solute.
• Common colligative properties include vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure.

Acids and Bases

• Acids are substances that release hydrogen ions (H+) in solution.
• Bases are substances that release hydroxide ions (OH-) in solution or accept H+.
• The pH scale measures the acidity or basicity of a solution.
• Strong acids and bases completely dissociate in water.
• Weak acids and bases only partially dissociate.
• Neutralization reactions occur when acids and bases react to form water and a salt.
• Indicators are used to determine the approximate pH of a solution.

Stoichiometry

• Stoichiometry is the quantitative relationship between reactants and products in a chemical reaction.
• Stoichiometric calculations use balanced chemical equations to determine amounts of substances involved.
• These calculations often involve moles, molar mass, and the mole ratio from the balanced equation.

Thermodynamics

• Thermodynamics describes the energy changes in chemical and physical processes.
• The first law of thermodynamics states that energy can be neither created nor destroyed, only transformed.
• The second law of thermodynamics deals with the spontaneity of reactions.
• The third law of thermodynamics relates the entropy of a substance to its absolute temperature.
• Enthalpy (ΔH) represents the heat absorbed or released in a reaction at constant pressure.
• Entropy (ΔS) measures the disorder or randomness of a system.
• Gibbs free energy (ΔG) combines enthalpy and entropy to determine if a reaction is spontaneous at a given temperature.

Periodic Table

• The periodic table organizes elements based on their atomic number and recurring chemical properties.
• Elements are categorized into groups (vertical columns) and periods (horizontal rows).
• Elements within a group share similar chemical properties due to their valence electron arrangements.
• Trends in atomic radii, ionization energy, and electronegativity are observed across the table.

Organic Chemistry

• Organic chemistry is the study of carbon-containing compounds.
• Organic molecules exhibit diverse structures and reactivities.
• Hydrocarbons, alcohols, aldehydes, ketones, carboxylic acids, and amines are common functional groups.
• Isomerism can occur in organic molecules with the same molecular formula but different structures.