The Bohr-Rutherford Atom

The Bohr-Rutherford Atom

The Bohr-Rutherford Atom Nils Bohr Ernest Rutherford Physics 100 Chapt 23 1895 J.J. Thomson discovered

electron Vacuum flask - + ++ ++ ---

cathode cathode rays anode Cathode rays have negative charge and very small mass S -

+ ++ ++ --- cathode anode N

m=0.0005MHydrogen Plum pudding? Positively charged porridge Negatively charged raisins (plums) ++ +

+ - + + + + + + + + -+ -+ - +

+ 10-10m Planetary-like? Positively charged ense central nucleus - +

- - 10-10m Negatively charged orbiting electrons Rutherford Experiment Vacuum

flask -rays Whats in the box? Is all the mass spread throughout as in a box of marshmallows? or is all the mass concentrated in a dense

ball-bearing? Figure it out without opening (or shaking) Shoot bullets randomly through the box. If it is filled with marshmallows, all the bullets will go straight through without (much) deflection Figure it out without opening (or

shaking) If it contains a ball-bearing most the bullets will go straight through without deflection--but not all Occasionally, a bullet will collide nearly headon to the ball-bearing and be deflected by a large angle Rutherford used -ray bullets to distinguish between the plumpudding & planetary models Plum-pudding:

++ + + - + + + + +

+ + + -+ -+ - + + no way for -rays to scatter at wide angles

distinguishing between the plumpudding & planetary models - + -

- Occasionally, an-rays will be pointed head-on to a nucleus & will scatter at a wide angle Rutherford saw ~1/10,000 a-rays scatter at wide angles -

+ - - from this he inferred a nuclear size of about 10-14m

Rutherford atom 10-10m Not to scale!!! 10-14m + If it were to scale,

the nucleus would be too small to Even though it see has more than 99.9% of the atoms mass

Relative scales Aloha stadium Golf ball x10-4 Atom Nucleus 99.97% of the mass

Classical theory had trouble with Rutherfords atom Orbiting electrons are accelerating Accelerating electrons should radiate light According to Maxwells theory, a Rutherford atom would only survive for only about 10-12 secs

sola Other peculiar discoveries: Solar light spectrum: raunhofer discovered that some wavelengths a missing from the suns black-body spectrum Other discoveries Low pressure gasses, when heated, do not radiate black-body-like spectra; instead they radiate only a few specific colors

bright colors from hydrogen match the missing colors in sunlight Hydrogen spectrum Solar spectrum Allowed orbits Bohrs idea

Hydrogen energy levels 4 3 1 + Hydrogen energy levels 2

1 + What makes Bohrs allowed energy levels allowed? Recall what happens when we force waves into confined spaces: Confined waves nly waves with wavelengths that just fit in surviv

(all others cancel themselves out) Electrons in atoms are confined matter waves ala deBroglie However, if the circumference is exactly an integer number of wavelengths, This wave, as it goes around, will successive

interfere turns will interfereand constructively with itself destructively cancel itself out Bohrs allowed energy states correspond to those with orbits that are integer numbers of wavelengths Bohr orbits

Bohr orbits Quantum Mechanics Erwin Schrodinger Schrodingers equation Matter waves are probability waves Probability to detect the electron at some place

is 2 at that spot Electrons will never be detected here or here Electrons are most likely to be detected here

Quantum mechanical atom Bohrs original idea Probability density Quantum Mechanics Different QM states of the H atom

Recently Viewed Presentations

  • Species Interactions Gauses Principle of Competitive Exclusion In

    Species Interactions Gauses Principle of Competitive Exclusion In

    Species interactions help define communities and ecosystems. Competition can come in many different forms (lions and hyenas in upper right) or food partitioning in Anolis. lizards (lower left). In upper right is an example of parasitism of snail species where...
  • 7. Phosphorus Fertilizers SOIL 5813 Soil-Plant Nutrient Cycling

    7. Phosphorus Fertilizers SOIL 5813 Soil-Plant Nutrient Cycling

    email: [email protected] Tel: (405) 744-6414 Phosphorus Use Efficiency ? Rock Phosphate Ca10(PO4)6(OH)2 Hydroxyapatite (bones, teeth) "bone-meal" bones in acid soils? Ca10(PO4)6F2 or Cl2 or OH2 Fluorapatite 27-41% P2O5 Total P in soils (90 to 2000 lb /acre, avg. of 800...
  • The Brain

    The Brain

    The human brain is the command center for the human nervous system. It receives input from the sensory organs and sends output to the muscles. It is responsible for the conscious communication with our body and for the automatic operation...
  • Case Study: Ford Motor Company Assignment: Ford and

    Case Study: Ford Motor Company Assignment: Ford and

    - Caroline Pernot, Ford car communications Case Study: Ford Motor Company Result: Filmaka received 400 scripts in only two weeks from filmmakers in 28 countries on six continents. After Ford/JWT/Filmaka reviewed scripts and Filmaka vetted the directors, 22 films were...
  • A Collaborative Effort to Evaluate Water Resources in

    A Collaborative Effort to Evaluate Water Resources in

    Suzanne Moellendorf, GSI Water Solutions, Inc. Mike Miller, City of Florence. Dennis Nelson, GSI Water Solutions, Inc. Dave Livesay, GSI Water Solutions, Inc. ... PRELIMINARY RESULTS: GroundwaterWater Table Elevation Contours (feet above sea level) Contours vary from 20-100 ft in...
  • BBMS Computer Lab

    BBMS Computer Lab

    How to Login, Create, & Save Your Stuff! BBMS iMac Lab Student Orientation
  • Information Literacy: more than just a library induction

    Information Literacy: more than just a library induction

    You must ensure any advice you give is evidence based if you are suggesting healthcare products or services" NMC 2008 Code of Professional Conduct London, NMC According to a 2008 report by UCL "Information behaviour of the researcher of the...
  • 1Copyright  2016, Oracle and/or its affiliates. All rights

    1Copyright 2016, Oracle and/or its affiliates. All rights

    The Bills and Collections (BC) module supports the processing of all types of bills, both domestic and international. It handles the necessary activities during the entire lifecycle of a bill once it is booked. Accelerator Pack - BC. Introduction.