Chemistry Atomic Structure and Bonding

Atomic Structure

• Atoms are the basic building blocks of matter.
• Composed of a nucleus containing protons (positively charged) and neutrons (neutral).
• Electrons (negatively charged) orbit the nucleus.
• Atomic number is the number of protons.
• Mass number is the sum of protons and neutrons.
• Isotopes are atoms of the same element with different numbers of neutrons.
• Electron configuration describes the arrangement of electrons in energy levels and sublevels.

Chemical Bonding

• Atoms bond to achieve a stable electron configuration, typically by filling their outermost electron shell.
• Ionic bonding involves the transfer of electrons between atoms, forming ions (charged particles).
• Covalent bonding involves the sharing of electrons between atoms.
• Metallic bonding involves the sharing of free electrons among a lattice of metal atoms.
• Intermolecular forces are attractive forces between molecules.
• Types include: hydrogen bonding, dipole-dipole forces, and London dispersion forces.

Chemical Reactions

• Chemical reactions involve the rearrangement of atoms to form new substances.
• Reactants are the starting materials.
• Products are the substances formed by the reaction.
• Chemical equations represent reactions, showing reactants and products.
• Balanced equations have equal numbers of atoms of each element on both sides.
• Types of chemical reactions include: synthesis, decomposition, single-displacement, double-displacement, and combustion.

States of Matter

• Matter exists in solid, liquid, and gaseous states.
• Solids have fixed shape and volume.
• Liquids have a definite volume but take the shape of their container.
• Gases have neither fixed shape nor volume, filling their container completely.
• Changes of state involve changes in energy.

Stoichiometry

• Stoichiometry is the quantitative study of reactants and products in a chemical reaction.
• Mole concept is fundamental in stoichiometry.
• Molar mass is the mass of one mole of a substance.
• Mole ratios from balanced equations are crucial for stoichiometric calculations.

Solutions

• Solutions are homogeneous mixtures of two or more substances.
• Solvent is the substance present in the largest amount.
• Solute is the substance dissolved in the solvent.
• Concentration describes the amount of solute in a given amount of solvent or solution (e.g., molarity, molality, percent by mass).

Acids and Bases

• Acids are substances that donate protons (H+ ions) in an aqueous solution.
• Bases are substances that accept protons.
• pH scale measures acidity or basicity (0-14).
• Neutral solutions have a pH of 7.
• Strong acids and bases completely dissociate in water.
• Weak acids and bases only partially dissociate.

Thermodynamics

• Thermodynamics deals with energy changes in chemical reactions.
• Exothermic reactions release heat to the surroundings.
• Endothermic reactions absorb heat from the surroundings.
• Enthalpy (H) is a measure of the heat content of a system.
• Entropy (S) measures the disorder or randomness of a system.
• Gibbs free energy (G) determines spontaneity of a reaction.

Kinetics

• Kinetics studies the rates of chemical reactions.
• Reaction rate is the speed at which reactants are consumed or products are formed.
• Factors affecting reaction rate include concentration, temperature, catalysts, and surface area.
• Collision theory explains how reactions occur by collisions between molecules.

Equilibrium

• Equilibrium is the state where the rates of forward and reverse reactions are equal.
• Le Chatelier's principle describes how a system at equilibrium responds to changes in conditions (temperature, pressure, concentration of reactants or products).