Nature of Matter and Laws of Chemical Combination

The basic rules governing how substances combine, discovered long before atoms could be directly observed.

States and Properties of Matter

Matter exists in three common physical states — solid, liquid and gas — and has both physical and chemical properties, which can be measured quantitatively or qualitatively.

Laws of Chemical Combination

  • Law of Conservation of Mass — mass is neither created nor destroyed in a chemical reaction
  • Law of Definite Proportions — a compound always contains the same elements in the same fixed proportion by mass
  • Law of Multiple Proportions — when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other are in small whole-number ratios

Dalton's Atomic Theory

Proposed that matter is made of indivisible atoms, and that atoms of the same element are identical — this theory successfully explained the laws of chemical combination.

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