Early Ideas in Atomic Theory

Vocabulary flashcards covering early ideas in atomic theory, Dalton's postulates, and the laws of conservation of matter, definite proportions, and multiple proportions.

Atomos

A term derived from the Greek word for 'indivisible,' used by fifth-century BC philosophers Leucippus and Democritus to describe small, finite particles that compose all matter.

Aristotelian View of Matter

The view holding that matter consists of various combinations of four 'elements'—fire, earth, air, and water—and can be infinitely divided.

John Dalton

An English schoolteacher who published an atomic theory in 1807 proposing microscopic hypotheses to explain the macroscopic behavior of matter.

Dalton's Postulate on Atoms

The principle stating that matter is composed of exceedingly small particles called atoms, which are the smallest unit of an element that can participate in a chemical change.

Dalton's Postulate on Elements

The principle stating that an element consists of only one type of atom, which has a mass characteristic of the element and is identical across all atoms of that element.

Dalton's Postulate on Compounds

The principle stating that a compound consists of atoms of two or more elements combined in a small, whole-number ratio.

Dalton's Postulate on Chemical Changes

The principle stating that atoms are neither created nor destroyed during a chemical change, but are instead rearranged to yield different substances.

Law of Conservation of Matter

The principle stating that the total mass of matter remains constant when matter changes from one type to another because atoms are neither created nor destroyed.

Joseph Proust

The French chemist who demonstrated that all samples of a pure compound contain the same elements in the same proportion by mass.

Law of Definite Proportions

Also known as the law of constant composition; states that all samples of a pure compound contain the same elements in the same proportion by mass.

Isooctane

A component of gasoline and standard in the octane rating system that consistently exhibits a carbon-to-hydrogen mass ratio of $5.33:1.00$ across all samples.

Law of Multiple Proportions

The law stating that when two elements react to form more than one compound, a fixed mass of one element will react with masses of the other element in a ratio of small, whole numbers.

Copper(II) oxide

A powdery, black compound resulting from the combination of copper atoms (brown spheres) and oxygen atoms (red spheres) in a $1:1$ ratio.

Copper Chlorine Compounds

Two crystalline compounds where the brown compound contains a mass ratio of $1.116\,\text{g}$ Cl per $1\,\text{g}$ Cu and the green compound contains $0.558\,\text{g}$ Cl per $1\,\text{g}$ Cu, forming a $2:1$ ratio of chlorine content.