Lecture_4--Atomic_Theory_and_Isotopes

Lecture_4--Atomic_Theory_and_Isotopes - Atomic Theory &...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Atomic Theory & Isotopes Chapter 2 Democritus (5 th – 4 th century BC) ATOMISM Aristotle (4 th – 5 th century BC) CONTINUOUS MATTER FOUR ELEMENTS – Earth, Air, Fire, Water Boyle (17 th century) Reintroduced ATOMISM in modern times. Dalton (19 th century) Atomic Theory to explain results of EXPERIMENTS. Theories of Matter Composition Development of the Modern Atomic Theory In 1803, John Dalton proposed an atomic theory that is still the basis for many of our theories about the atom. 1. All matter is composed of atoms, which are tiny, indivisible particles. 2. A chemical reaction is a rearrangement of atoms to form different compounds. Atoms are neither created nor destroyed in a chemical reaction (the law of conservation of mass). 3. Atoms of one element cannot be converted into another element. Atoms of an element are identical in mass and other properties, and are different from every other element. 4. A compound is a combination of atoms of two or more elements in specific ratios (the law of definite composition).
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 J.J. Thompson and the Discovery of the Electron. Electron: Very small, subatomic, negatively charged particle. Cathode Ray Tube: From his experiments, Thompson calculated the ratio of the electron’s mass, m e , to its electric charge, e . Millikan's Oil-drop Experiment The work of Thomson and Millikan combined provided us with the electron’s mass of 9.109 x 10-31 kg , which is more than 1800 times smaller than the mass of the lightest atom (hydrogen). These experiments also showed that the electron is a subatomic particle.
Background image of page 2
3 Thomson’s Atomic Theory: JJ Thomson favored the plum pudding model . He believed that the
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/19/2011 for the course CHEM 230 taught by Professor Levi during the Spring '11 term at Skyline College.

Page1 / 9

Lecture_4--Atomic_Theory_and_Isotopes - Atomic Theory &...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online