This lecture covers the fundamentals of chemical stoichiometry, including quantities of substances, balancing chemical reactions, and the concept of the mole. It also delves into the macroscopic and microscopic aspects of matter, such as atomic and molecular masses, molar mass, and the kinetic theory of gases. Additionally, it explores the ideal gas law, standard conditions, partial pressures in gas mixtures, and concentration units for solutions. The lecture concludes with discussions on reaction stoichiometry, limiting reactants, and yield calculations through practical examples and exercises.