CHEM 1030 Chapter 2: Atoms, Molecules, and Ions

• School: Auburn University
• Department: Chemistry
• Course: CHEM 1030
• Professor: Marla Spergel

Document Summary

Atomic theory of matter: the theory that atoms are the fundamental building blocks of matter reemerged in the early 19th century, championed by john dalton. Law of constant composition: joseph proust (1754 1826: this is also known as the law of definite proportions; states that the elemental composition of a pure substance never varies. Law of conservation of mass: the total mass of substances present at the end of a chemical process is the same as the mass of substances present before the process took place. The electron: streams of negatively charged particles were found to emanate from cathode tubes, j. j. thompson is credited with their discovery (1897). Thompson measured the charge/mass ratio of the electron to be 1. 76 108 coulombs/g. Radioactivity - the spontaneous emission of radiation by an atom. It was first observed by henri becquerel; marie and pierre curie also studied it: three types of radiation were discovered by ernest rutherford: