PHYSICS 002C Lecture 24A

PHYSICS 002C Lecture 24A - PHYSICS 002C Lecture 24 May 27,...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
PHYSICS 002C Lecture 24 May 27, 2009 Serway and Jewett Chapter 29 – Atomic Physics Do atoms exist or are they just a concept used for chemical formulae, etc? Why can we see these atoms if they are complex probability amplitude waves? Answer: Because they are stuck on the surface and can’t move; their phases are all mixed up with the millions of atoms of the surface and solid. Chap 29.1 Early Models of Atoms Lucretius (94-49 BC) thought atoms were tiny and had different shapes. “All Nature consists of particles and the vacuum in which they move.” Dalton (1805) Law of multiple proportions implies the existence of atoms. Lavoisier (1743-1794) Disproved the phlogiston theory. Priestley Discovery of oxygen. During the 19 th century, evidence for the existence of atoms and knowledge of their properties advanced far beyond Lucretius. Faraday [ Phil. Trans. Roy. Soc. 124 , 77 (1834)] discovered that a certain amount of charge is associated with the production of a certain mass of product by electrolysis. Don Eigler and his quantum corral of Xe atoms on a Cu surface. One faraday = 96,519 C is associated with the production of one gram molecular weight of product. Menedleev (1870) arranged the periodic table of elements from the periodicity evident in a plot of atomic volume versus atomic weight, and from the similarity of chemistry for every 8 th element. (Newlands, 1865). Exceptions to the arrangement by weights suggested there was more to learn, eg. Ar [A=39.88] and K [A=39.10], where A is the atomic mass in units where the oxygen atom has A = 16. The atomic masses A are very nearly integral, lending support to Wm. Prout’s suggestion that all the elements are made of hydrogen. However chlorine Cl has a weight of 35.46 so it appeared not so. J. J. Thomson [ Phil. Mag. 44 , 293 (1897)] measured e / m for the electron. Atomic model of exonuclease eating one strand of DNA. R. A. Millikan [1909] measured e via his oil drop experiment. Thus m = mass of H / 1836. John Dalton and his atoms
Background image of page 1

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

View Full DocumentRight Arrow Icon
Dalton’s atomic theory (1805) 1. Elements are made of tiny particles called atoms. 2. All atoms of a given element are identical. 3. The atoms of a given element are different from those of any other element. 4. Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers of types of atoms. 5. Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process. A chemical reaction simply changes the way atoms are grouped together. 6. Atoms combine only in pairs, so water is OH etc.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 06/08/2009 for the course PHYS 2c taught by Professor All during the Spring '08 term at UC Riverside.

Page1 / 7

PHYSICS 002C Lecture 24A - PHYSICS 002C Lecture 24 May 27,...

This preview shows document pages 1 - 3. Sign up to view the full document.

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