Philosophy and Chemistry: Matter Concepts

Ancient Philosophers' Ideas on Matter

• Ancient Indian philosophers, like Maharishi Kanad (around 500 BC), proposed the divisibility of matter.
• Kanad hypothesized progressively smaller particles ("Parmanu") until a point of indivisibility.
• Another Indian philosopher, Pakudha Katyayama, elaborated on the combined nature of these particles.
• In ancient Greece, Democritus and Leucippus also theorized indivisible particles, calling them "atoms."
• These ideas were primarily philosophical, lacking experimental backing until the 18th century.

18th-Century Developments in Chemistry

• By the late 1700s, scientists recognized elements and compounds.
• They wanted to understand how elements combine and the resulting changes.
• Antoine Lavoisier established fundamental laws of chemical combination.

Laws of Chemical Combination

Law of Conservation of Mass

• Mass remains constant during a chemical reaction.
• Experimental verification involves weighing a reaction flask with and without reacting substances.
• Key takeaway: Mass is neither created nor destroyed.

Law of Constant Proportions (Definite Proportions)

• Compounds always contain elements in fixed mass ratios.
• Examples include water (H:O = 1:8) and ammonia (N:H = 14:3).
• Proust stated this law: Elements in a chemical substance have a constant ratio by mass.

Dalton's Atomic Theory

• John Dalton built on the concept of atoms (Greek origins), arguing that they're the smallest matter units.
• His atomic theory explained the conservation of mass and constant proportions laws.
• All matter (elements, compounds, and mixtures) consist of atoms.