Atomic Structure and Chemical Bonding

Atomic Structure

• Atoms are the fundamental building blocks of matter.
• Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons.
• Protons have a positive charge, electrons have a negative charge, and neutrons have no charge.
• The atomic number represents the number of protons in an atom.
• The mass number represents the total number of protons and neutrons.
• Isotopes are atoms of the same element with different numbers of neutrons.
• Electron configuration describes the arrangement of electrons in different energy levels and sublevels within an atom.

Chemical Bonding

• Chemical bonds hold atoms together to form molecules.
• Ionic bonds form between a metal and a nonmetal, where one atom loses electrons and the other gains them.
• Covalent bonds form between two nonmetals, where atoms share electrons.
• Metallic bonds form between metal atoms, where electrons are delocalized and shared among many atoms.
• Electronegativity is the ability of an atom to attract electrons in a chemical bond.

Chemical Reactions

• Chemical reactions involve the rearrangement of atoms to form new substances.
• Reactants are the starting materials in a chemical reaction.
• Products are the resulting substances formed in a chemical reaction.
• Chemical equations represent chemical reactions using chemical formulas and symbols.
• The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction.
• Balancing chemical equations ensures that the number of atoms of each element is the same on both sides of the equation.
• Different types of chemical reactions include synthesis, decomposition, single displacement, double displacement, and combustion.

States of Matter

• Matter exists in different states: solid, liquid, and gas.
• Solids have a fixed shape and volume.
• Liquids have a fixed volume but take the shape of their container.
• Gases have neither a fixed shape nor a fixed volume.
• Phase changes involve transitions between these states (e.g., melting, freezing, vaporization, condensation, sublimation).

Stoichiometry

• Stoichiometry is the quantitative relationship between reactants and products in a chemical reaction.
• Mole concept relates the mass of a substance to the number of moles.
• Molar mass is the mass of one mole of a substance.
• Stoichiometric calculations allow us to determine the amounts of reactants and products in a chemical reaction.

Solutions

• A solution is a homogeneous mixture of two or more substances.
• The solute is the substance that is dissolved.
• The solvent is the substance that dissolves the solute.
• Concentration describes the amount of solute dissolved in a given amount of solvent.
• Different concentration units exist (e.g., molarity, molality, percent by mass).

Acids and Bases

• Acids are substances that produce hydrogen ions (H+) when dissolved in water.
• Bases are substances that produce hydroxide ions (OH-) when dissolved in water.
• The pH scale measures the acidity or basicity of a solution.
• Strong acids and bases completely dissociate in water, while weak acids and bases only partially dissociate.
• Neutralization reactions occur when an acid and a base react to form a salt and water.

Thermodynamics

• Thermodynamics deals with energy changes in chemical and physical processes.
• Exothermic reactions release heat to the surroundings.
• Endothermic reactions absorb heat from the surroundings.

Organic Chemistry

• Organic chemistry is the study of carbon-containing compounds.
• Hydrocarbons are organic compounds composed only of carbon and hydrogen.
• Functional groups are specific groups of atoms within organic molecules that determine their chemical properties.
• Isomers are molecules with the same molecular formula but different structures.

Kinetics

• Chemical kinetics studies the rates of chemical reactions.
• Factors affecting reaction rates include temperature, concentration of reactants, presence of catalysts, and surface area.
  • The Arrhenius equation describes the relationship between reaction rate and temperature.