Philosophy and Chemistry Quiz

Ancient Indian and Greek Philosophers

• Ancient Indian and Greek philosophers pondered the divisibility of matter
• Indian philosopher Maharishi Kanad proposed that matter could be divided into smaller and smaller particles, eventually reaching indivisible particles called Parmanu
• Greek philosophers Democritus and Leucippus suggested indivisible particles called atoms
• These ideas were based on philosophical reasoning rather than experimentation

Law of Conservation of Mass

• Lavoisier and Proust demonstrated that mass is conserved in a chemical reaction
• This means the total mass of the reactants equals the total mass of the products

Law of Constant Proportions

• Lavoisier and Proust observed that elements always combine in fixed proportions to form a given compound
• This proportion is constant regardless of the source or method used to prepare the compound

Dalton's Atomic Theory

• Dalton proposed an atomic theory based on the laws of chemical combination
• Key postulates of the theory:
  • All matter is made of atoms
  • Atoms are indivisible and indestructible
  • Atoms of the same element are identical in mass and properties
  • Atoms of different elements have different masses and properties
  • Atoms combine in whole number ratios to form compounds

Atomic Mass

• Atomic mass is the relative mass of an atom compared to 1/12 the mass of a carbon-12 atom
• This is a relative value, not an absolute one
• Dalton's theory explained the law of conservation of mass and the law of constant proportions

Atoms, Molecules, and Ions

• Atoms of most elements do not exist independently, they exist as molecules or ions
• Molecules are groups of atoms chemically bonded together
• Atoms of the same element may form molecules of different compositions or atomicity
• Ions are charged particles, either negative (anions) or positive (cations)

Chemical Formulae

• Chemical formula provides a symbolic representation of composition
• The rules for writing chemical formulae:
  • Valency determines the number of atoms in a compound
  • Use brackets for compounds containing multiple polyatomic ions
• Simple compounds are made of two types of elements