1. Chapter 4 Atomic Structure

2. A Long, Long Time Ago… Greek Philosophers- 4 elements are Earth, Water, Fire, and Air Greek Philosophers- 4 elements are Earth, Water, Fire, and Air Aristotle- first recorded atomic thoughts Aristotle- first recorded atomic thoughts Matter is continuous (no atoms) Matter is continuous (no atoms) Democritus (400 B.C.) - first recorded atomic theory Democritus (400 B.C.) - first recorded atomic theory Atoms are smallest part of matter, each type of matter has different atoms Atoms are smallest part of matter, each type of matter has different atoms

3. Aristotle and Democritus

4. A Long Time Ago… Antoine Lavoisier (1782) Antoine Lavoisier (1782) –Used experiments in closed containers to develop the LCM Joseph Proust (1799) Joseph Proust (1799) –Analyzed water to develop the Law of Definite Proportions John Dalton (1803) John Dalton (1803) –Compiled past research to develop the first useful atomic theory

5. Lavoisier and Proust

6. John Dalton Dalton’s theory had 4 major tenets Dalton’s theory had 4 major tenets 1.All matter is composed of atoms 2.Atoms are indivisible 3.Atoms of 1 element are alike, but different from those of other elements 4.Atoms combine in small, whole number ratios to form compounds

7. A Reminder Observation, Observation, Observation Observation, Observation, Observation Research Research Hypothesis Hypothesis Experiment, Revise hypothesis lots of times Experiment, Revise hypothesis lots of times Results match….may become a theory Results match….may become a theory

8. A Little While Ago… 1897- J.J. Thomson discovers the electron using a cathode ray tube 1897- J.J. Thomson discovers the electron using a cathode ray tube

9. Cathode Ray Tube Experiment http://www.aip.org/history/electron/jjappara. htm http://www.aip.org/history/electron/jjappara. htm http://www.aip.org/history/electron/jjappara. htm

10. The Nucleus Exists! 1911- Ernest Rutherford uses the gold foil experiment to “discover” the nucleus 1911- Ernest Rutherford uses the gold foil experiment to “discover” the nucleus

11. The Gold Foil Experiment

12. Results of Gold Foil Experiment… http://online.cctt.org/physicslab/content/Phy1/lesso nnotes/atomic/atomicmodelsandspectra.asp http://online.cctt.org/physicslab/content/Phy1/lesso nnotes/atomic/atomicmodelsandspectra.asp http://online.cctt.org/physicslab/content/Phy1/lesso nnotes/atomic/atomicmodelsandspectra.asp http://online.cctt.org/physicslab/content/Phy1/lesso nnotes/atomic/atomicmodelsandspectra.asp http://micro.magnet.fsu.edu/electromag/java/ruthe rford/ http://micro.magnet.fsu.edu/electromag/java/ruthe rford/ http://micro.magnet.fsu.edu/electromag/java/ruthe rford/ http://micro.magnet.fsu.edu/electromag/java/ruthe rford/ Over 98% of the particles went straight through Over 98% of the particles went straight through About 2% of the particles went through but were deflected by large angles About 2% of the particles went through but were deflected by large angles About 0.01% of the particles bounced off the gold foil About 0.01% of the particles bounced off the gold foil

13. Rutherford’s Conclusion

14. Rutherford's Nuclear Model 1. The atom contains a tiny dense center called the nucleus 1. The atom contains a tiny dense center called the nucleus –the volume is about 1/10 trillionth the volume of the atom 2. The nucleus is essentially the entire mass of the atom 2. The nucleus is essentially the entire mass of the atom 3. The nucleus is positively charged 3. The nucleus is positively charged –the amount of positive charge of the nucleus balances the negative charge of the electrons 4. The electrons move around in the empty space of the atom surrounding the nucleus 4. The electrons move around in the empty space of the atom surrounding the nucleus

15. Understanding Periodic Blocks 19 19 K 39.0983 39.0983 Atomic Number Atomic Number –# of protons Element Symbol Element Symbol Mass Number Mass Number –Protons + Neutrons

16. Can 20.0983 Neutrons Exist??? No, 39.0983 is an average mass of all natural K atoms No, 39.0983 is an average mass of all natural K atoms –All K atoms MUST have 19 protons –Some have 20 neutrons, some 19, some 21… –Average is 20.0983 neutrons –Individual isotopes are identified by the number of neutrons

17. Identifying Protons, Neutrons, and Electrons Chlorine-35 (element-mass number) Chlorine-35 (element-mass number) # of protons = 17 # of protons = 17 # electrons = # protons # electrons = # protons # neutrons = mass number – protons # neutrons = mass number – protons –35-17 = 18 Why no electrons in atomic mass? Why no electrons in atomic mass? –Electron has mass 1/1837 of Proton and Neutron

18. Nuclear Stability

19. The Modern View of the Atom Neils Bohr (1913) develops the planetary model of the atom Neils Bohr (1913) develops the planetary model of the atom –Developed from “electrocution” of hydrogen gas –Only certain colors resulted –Why??? http://www.colorado.edu/physics/2000/qua ntumzone/index.html http://www.colorado.edu/physics/2000/qua ntumzone/index.html http://www.colorado.edu/physics/2000/qua ntumzone/index.html http://www.colorado.edu/physics/2000/qua ntumzone/index.html

20. Bohr’s Hydrogen Atom http://www.visionlearning.com/library/m odule_viewer.php?mid=51 http://www.visionlearning.com/library/m odule_viewer.php?mid=51

21. Schrodinger’s Revision… http://www.colorado.edu/physics/2000/quantumzone/schroedinger.html