Atomic Theory and Fundamental Chemical Laws

Vocabulary flashcards reviewing fundamental chemical laws, Dalton's atomic theory, and key historical atomic experiments based on lecture notes.

Law of Definite Proportions

A rule stating that a given chemical compound always contains the same elements in the same proportions by mass.

Dalton's Atomic Theory (Postulate 1)

States that elements are composed of indestructible particles called atoms. This postulate is false because atoms are NOT indestructible.

Dalton's Atomic Theory (Postulate 2)

States that all atoms of a given element are identical and that the atoms of one element are different from all other elements. This postulate is false because they are not identical.

Dalton's Atomic Theory (Postulate 3)

States that compounds are composed of atoms of more than one element. This postulate is true.

Dalton's Atomic Theory (Postulate 4)

States that a chemical reaction involves only the separation, combination, or rearrangement of atoms, and does not result in their creation or destruction. This postulate is true.

Law of Conservation of Mass

States that mass is neither created nor destroyed during a chemical reaction, meaning the mass of reactants equals the mass of products.

Cathode Ray Tube Experiment

An experiment conducted by J.J. Thomson where a beam traveled from a negative electrode and was deflected by electromagnetic fields, behaving identically regardless of the metal used, demonstrating that the beam was made of electrons and establishing their charge-to-mass ratio.

Millikan's Oil Drop Experiment

An experiment where tiny oil droplets were sprayed between charged metal plates and suspended by balancing gravitational and electrical forces; calculated charges were all multiples of a single value, proving electrical charge is quantized and allowing the determination of the electron's charge.

Rutherford's Gold Foil Experiment

An experiment where alpha particles were fired at a thin sheet of gold foil and detected by a fluorescent screen; most passed straight through while a few bounced straight back, showing that positive charge is concentrated in a small region.

Nucleus

A tiny, dense, positively charged center of the atom that contains most of the atom's mass, discovered via Rutherford's Gold Foil Experiment.

James Chadwick

The scientist who confirmed the existence of the neutron, which explained the missing mass or mass deficit in atomic nuclei where atomic masses were greater than protons alone could account for.