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Scientific Thought Evolves Over Time Atoms Gravity Space-Time Theory of Everything???

History of the Atom. Scientific Thought Evolves Over Time Atoms Gravity Space-Time Theory of Everything??? Based on Pure Thought or What Is Observable At The Time. Ancient Greek Thought [460-370 B.C.]. Aristotle: 4 elements of fire, water, earth and air. Observation: Effects of Burning

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Scientific Thought Evolves Over Time Atoms Gravity Space-Time Theory of Everything???

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  1. History of the Atom • Scientific Thought Evolves Over Time • Atoms • Gravity • Space-Time • Theory of Everything??? • Based on Pure Thought or What Is Observable At The Time

  2. Ancient Greek Thought [460-370 B.C.] • Aristotle: 4 elements of fire, water, earth and air. • Observation: Effects of Burning • Democritus: “ATOMOS” Smallest Unit into Which Something May be Divided • Observation: Slicing of Bread

  3. DaltonEnglish 1808 • Dalton – brought back idea of Democritus • Thought that atoms are smallest unit of matter • But, thought that each element had a unique atom – they were all different.

  4. Sir J. J. ThompsonEnglish 1904 Physics 1906 • Cathode Ray Tube Experiment – discovered electrons! • “Plum Pudding Model” • Thought atoms where a + charged sphere or glob of matter with bits of – charged particles – like a pudding with large plums. • Plum pudding was a favorite in Victorian Britain at the time.

  5. Cathode Ray Experiment

  6. Ernest RutherfordEnglish 1908 Chemistry 1908 • Gold Foil Experiment • Discovered the Nucleus! • Showed Mass of Atom concentrated in + charged nucleus, • Nucleus is surrounded by electrons • Atom is Mostly Empty Space • Similar to Planetary System

  7. Gold Foil Experiment

  8. Neils BohrDanish 1915 Physics 1922 • Thought electrons orbited the nucleus in orbits, like planets, but only in predictable, fixed locations • Locations were called “energy levels”, which were similar to gravitational potential energy • This theory has been shown to be incorrect by Modern Physicists

  9. 1933 1932 Modern Atomic ModelElectron Cloud Shrodinger and Heisenberg • Electron Cloud Model • + Charged Nucleus • Surrounded by Cloud of – charged electrons • Cannot know the precise location of an electron at any given time – only its “Probable” place • Werner Heisenberg ( uncertainty principle and Erwin Schroedinger

  10. Electron Cloud Model

  11. Particles in an Atom Nucleus + Positive 1 amu Nucleus 1 amu None very small about 1/2000 amu Electron Cloud - Negative

  12. Basic Structure of an Atom(modern theory) The PROTONS are… In the NUCLEUS. The NEUTRONS are… In the NUCLEUS. The ELECTRONS are… In the ELECTRONCLOUD.

  13. This scanning tunneling microscope image clearly shows the individual atoms that make up this sheet of Au(100) surface. Reconstruction causes the surface atoms to deviate from the bulk crystal structure and arrange in columns several atoms wide with pits between them.

  14. Warm-Up Question Silk Cloth The ELECTRONS are being removed! ELECTRONS have a NEGATIVE charge. - When a glass rod is rubbed with a silk cloth, the rod becomes positively (+) charged. Make an inference about which subatomic particle is being removed. + - + - + - +

  15. Reading Homework Review Name the other two subatomic particles. Protons(p+) and Neutrons (n)

  16. Reading Homework Review What does the atomic number stand for? Number of protons …and therefore… Number of electrons

  17. Reading Homework Review How do you find the number of neutrons in an atom? - Mass Number Atomic Number Number of NEUTRONS

  18. Intro to Atoms to Content Map ATOMS Contains Nucleus Electrons Composed of Protons Neutrons Numbers added together make the Whose numbers are called the Atomic mass Atomic # Which Identifies Isotopes

  19. For Example… 11 Sodium Na 22.98977 Sodium’s ATOMIC # is That means sodium has 11p+ and 11e-

  20. In addition… 11 Sodium Na 22.98977 Sodium’s ATOMIC MASS # is 22.98977 rounded off is 23.

  21. Therefore… 11 Sodium Na 22.98977 23 (the MASS #) You can calculate the number of neutrons… -11 (the ATOMIC #) 12 (# of Neutrons)

  22. Drawing Models of Atoms

  23. So, to draw the Model: 11 Sodium Na 22.98977 There are 11 p+ 11p+

  24. So, to draw the Model: There are 11 e- 11 Sodium Na 22.98977 11p+

  25. So, to draw the Model: 11 Sodium Na 22.98977 23 – 11 = 12n 11p+ 12n

  26. Lab Essentials • Draw Electron Cloud models of atoms to show location and number of subatomic particles. • Describe protons, neutrons, and electrons. • Obtain information about an atom from the periodic table.

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