1. GPS 4 Atomic Theory Introduction to Chemistry

2. Objective  The student will investigate and understand that the placement of elements on the periodic table is a function of their atomic structure. The periodic table is used for investigations of (i) historical and quantum models. SOL CH-2i

3. Targets  CH-2i  I know the current model of the atom is called the quantum mechanical model.  I understand that the model of the atom has changed over time as new technology has led to new discoveries.

4. Targets Continued  Democritus  John Dalton  J.J. Thomson  Ernest Rutherford  Robert Millikan  Neils Bohr  Max Planck  Werner Heisenberg  Louis de Broglie  Erwin Schrodinger  I know the following scientists and their contributions to the current atomic model:

5. Vocabulary  scientists (listed above)  spherical model  planetary model  orbital model  quantum mechanics or wave model  gold foil experiment  cathode ray tube experiment  oil drop experiment

6. History of Atomic Theory  Democritus (400 B.C., Greece)  proposed that the world is made of empty space and tiny particles that he called “atoms”  John Dalton (1800s)  “solid sphere” model of the atom  first “modern” atomic theory of matter

7. History of Atomic Theory  J.J. Thomson (1897)  research with cathode-ray tube led to the discovery of the electron cathode-ray tube cathode-ray tube Plum Pudding Model

8. History of Atomic Theory  Robert Millikan (early 1900s)  discovered the charge on the electron (used oil drop experiment) oil drop experiment oil drop experiment

9. History of Atomic Theory  Ernest Rutherford (1912-1913)  gold foil experiment gold foil experiment gold foil experiment  The first to conclude that atoms have positive charges in their nucleus  discovered that atoms are mostly made of empty space

10. History of Atomic Theory  Ernest Rutherford (1912-1913)  discovered that atoms are mostly made of empty space Planetary Model

11. Discovery of the Neutron  J.J. Thomson  discovered isotopes (atoms that have the same number of protons and electrons, but have a different number of neutrons)  the existence of isotopes proved that part of the First Modern Atomic Theory is not completely correct.

12. History of Atomic Theory  Neils Bohr  discovered that excited atoms emit characteristic line spectra  Line spectra show us that electrons must be located at specific intervals (i.e. energy levels) around the nucleus Orbital Model

13. History of Atomic Theory  Max Planck  came up with the Quantum Theory, which states that energy is not given off continuously, but rather in little packets. He called these little packets of energy quanta (a.k.a. photons).  the amount of energy given off: E = hv v = the frequency of the light h = Planck’s constant (6.626 x 10-34 J/Hz) h = Planck’s constant (6.626 x 10-34 J/Hz)

14. Modern Atomic Theory  de Broglie  introduced his wave theory λ = h/(mv) λ = wavelength λ = wavelength h = Planck’s constant h = Planck’s constant m = mass v = velocity v = velocity ** Possible to predict the wavelength of a particle of mass (m) and velocity (v)

15. Modern Atomic Theory  Heisenberg uncertainty principle  it is impossible to know both the position and the momentum (velocity x mass) of an electron at the same time  energy levels – there is a higher probability of finding electrons in these areas than anywhere else in the atom

16. Modern Atomic Theory Wave-particle duality of nature  Light exhibits properties of both particles and waves.  Electrons also behave both as particles and waves (not at the same time- depends on the experiment) Quantum Mechanics  our current understanding of atomic structure and properties (our modern atomic theory)

17. Overview: Atomic Structure Dalton: Solid sphere model Thomson: Plum Pudding model Rutherford: Nuclear model Planetary model Bohr: Planetary model Orbital model de Broglie/Heisenberg: quantum mechanical Model

18. Today’s Model  Quantum Mechanical Model

19. Resources  http://www.chem.uiuc.edu/clcwebsite/cathode.html http://www.chem.uiuc.edu/clcwebsite/cathode.html  http://members.chello.nl/~h.dijkstra19/page7.html http://members.chello.nl/~h.dijkstra19/page7.html  http://physics.nad.ru/Physics/English/mill_txt.htm http://physics.nad.ru/Physics/English/mill_txt.htm  http://www.britannica.com/nobel/cap/omillik001a4.html http://www.britannica.com/nobel/cap/omillik001a4.html  http://en.wikipedia.org/wiki/Main_Page http://en.wikipedia.org/wiki/Main_Page  http://www.dlt.ncssm.edu/TIGER/chem1.htm http://www.dlt.ncssm.edu/TIGER/chem1.htm  http://mhsweb.ci.manchester.ct.us/Library/webquests/atomicmodel s.htm http://mhsweb.ci.manchester.ct.us/Library/webquests/atomicmodel s.htm http://mhsweb.ci.manchester.ct.us/Library/webquests/atomicmodel s.htm  http://phys- advlab.physics.lsa.umich.edu/Phys441_442/Atomic%2 0Spectroscopy/AtomicSpectroscopy.htm http://phys- advlab.physics.lsa.umich.edu/Phys441_442/Atomic%2 0Spectroscopy/AtomicSpectroscopy.htm http://phys- advlab.physics.lsa.umich.edu/Phys441_442/Atomic%2 0Spectroscopy/AtomicSpectroscopy.htm

20. SOL covered during lesson  CH 2 b, c, i

21. Dalton: First Modern Atomic Theory of Matter 1.All elements are composed of tiny indivisible particles called _________. 2. Atoms of the same element are _________. The atoms of any one element are different from those of any other element. atoms identical He = He He ≠ Cl

22. Dalton: First Modern Atomic Theory of Matter 3.Atoms of different elements can ___________ mix together or can chemically combine in simple whole-number ratios 4.Chemical reactions occur when atoms are separated, joined, or _________. Atoms of one element, however, are never changed into atoms of another never changed into atoms of another element as a result of a __________ reaction. rearranged chemical physically Physical mixture Chemical Reaction

23. Laws Law of conservation of mass - matter can not be created or destroyed, only changed in form Law of definite proportions - specific substances always contain elements in the same ratio by mass Law of multiple proportions - the proportion in which elements combine can be expressed in small whole numbers