Chemistry Chapter 3

1. Chemistry Chapter3 Atoms: The Building Blocks of Matter

2. Clicker ? How long have people been interested in understanding matter and its structure? • Thousands of years • Hundreds of years • A few years • Never

3. Ancient Philosophy Who:Aristotle, Democritus When: More than 2000 years ago Where: Greece What: Aristotle believed in 4 elements: Earth, Air, Fire, and Water. Democritus believed that matter was made of small particles he named “atoms”. Why: Aristotle and Democritus used observation and inferrence to explain the existence of everything.

4. Alchemists Who:European Scientists When: 800 – 900 years ago Where: Europe What: Their work developed into what is now modern chemistry. Why: Trying to change ordinary materials into gold.

5. Particle Theory

6. John Dalton

7. 1766-1844 Father of the atom Performed color blindness test Atomic Theory is a theory of the nature of matter Dalton model (Billiard Ball Model)

8. Dalton proposed the theory that elements are composed of indestructible atoms. Dalton stated that all atoms of one element were exactly alike, but that atoms of different elements were different form each other. He believed that an atom’s weight indicated the element to which it belonged and devised one of the first tables of atomic weights. He also believed that chemistry should be based on the atom and advanced the idea that atoms cannot be created or destroyed.

9. Particle Theory Who:John Dalton When: 1808 Where: England What: Described atoms as tiny particles that could not be divided. Thought each element was made of its own kind of atom. Why: Building on the ideas of Democritus in ancient Greece.

10. Henri Becquerel David Brooks Ricky Getch

11. What experiments did he perform? He performed experiments with the phosphorescence in light bulbs and the connection between x-rays and naturally occurring phosphorescence.

12. What theory or discovery did he make? Spontaneous radioactivity gasses could ionize and be deflected by electric or magnetic fields. Won the 1903 Nobel prize in the field of physics.

13. Particle Theory Who:Henri Becquerel When: 1896 Where: France What: Discovered radioactivity, the spontaneous emission of radiation by a material Why: Interested in fluorescence and phosphorescence

14. Discovery of Electrons

15. J.J. Thomson By: Averie and Chelsea

16. Discovery He discovered the electron and isotopes and he was also credited for the discovery of the mass spectrometer. Thomson’s experiments began in 1895, and were influenced by James Clerk Maxwell Assumed that cathode rays exhibited a single charge-to-mass ratio and must be made of a single type of negatively charged particle, which he called "corpuscles." Thomson is described as, “the man who first split the atom.” J.J. Thomson was awarded the Nobel Peace Prize in physics in 1906.

17. The primary function of this experiment was to see if the cathode ray was positive or negative because there was an electrometer, a device that measures the charge of an object. The magnetic field was produced with a Helmholtz galvanometer. Because of the magnetic fields, the cathode ray is spread out. If the electrostatic field is increased, then the magnetic field decreases This was used to test the conductivity of gas in the tube. It would show if the particles could separate.

18. Discovery of Electrons Who:J. J. Thompson When: 1897 Where: England What: Thompson discovered that electrons were smaller particles of an atom and were negatively charged. Why:Thompson knew atoms were neutrally charged, but couldn’t find the negative particle.

19. Robert A. Millikan Bree PortoIeshia Ross Marissa Elam

20. Oil Drop Experiment Experiment “The way this experiment works is that a droplet of oil will come out of an atomizer and go through a tiny slit in an electrode.  From the electrode the droplet will pass into a chamber with an electrode parallel from the electrode it had just passed.  In this chamber Millikan was able to balance or suspend the droplet by the charge the droplet had picked up when passing through the air.  Usining the amount of voltage needed to suspend the droplet he could then calculate the charge the the droplet.” -1896 http://library.thinkquest.org/28582/history/millexp.htm

21. Discovery Conclusion to Oil Drop Experiment When Millikan performed the oil drop experiment when he sprayed a very fine mist of oil and manipulated the falling rate of the oil using x-rays. He was able to measure the electron's charge, Millikan calculated the charge of an electron to be -1.602x10-19 columbs. Therefore, the mass had to be 9.109x1031 kg. Since the electron was found to have a negative charge, the implication existed that there must be a positive charge located somewhere in the atom since atoms are naturally neutrally charged.

22. The Atomic Model

23. Discovery of Electrons Who:R.A. Milikan When: 1909 Where: USA What: In his oil drop experiment, determined the charge and the mass of an electron.  Why:Wanted to find the negatively charged particles in an atom

24. Atomic Structure I

25. Ernest Rutherford

26. Experiments & Discoveries (1908) Discovered the concept of the “nucleus”. Main studies were alpha particles. He was the first to deliberately turn one element into another. He designed an experiment directing the alpha particles towards a thin metal foil. Surrounding the foil was a detector coated with a substance that produced flashes when hit by a particle. It was called “The Gold Leaf Experiment”.

27. His Experiment

28. Mr. Rutherford

29. Atomic Structure I Who: Ernest Rutherford When: 1911 Where: England What: Conducted an experiment to isolate the positive particles in an atom. Decided that the atoms were mostly empty space, but had a dense central core. Why: He knew that atoms had positive and negative particles, but could not decide how they were arranged.

30. Ernest Rutherford

31. Atomic Structure II

32. Niel Bohr

33. Theory/Discoveries 1915 Planetary Model The Manhattan Project Tube Alloy

34. Pictures Atomic Bomb Planetary Model Nobel Prize

35. Atomic Structure II Who: Niels Bohr When: 1913 Where: England What: Proposed that electrons traveled in fixed paths around the nucleus. Scientists still use the Bohr model to show the number of electrons in each orbit around the nucleus. Why: Bohr was trying to show why the negative electrons were not sucked into the nucleus of the atom.

36. Wave Nature of Atoms

37. Schrodinger Jackie Raye, Kayla Byrom, and Emily Boatwright

38. Schrodinger Wave Equation Quantum Numbers: (1) Principle quantum number, n, which gives rise to energy levels. (2) Magnetic quantum number, m, which gives rise to sublevels. (3) Azimuthal quantum number, l, which gives rise to orbitals. (4) Spin quantum number, s, which gives rise to orbital pairs of electrons. The equation accurately predicts the behavior of every electron in every atom.

39. Theory: there is no single outcome unless it is observed. The outcome due to what the quantum theory tells us that is true on a microscopic level vs. The outcome due to what our observations tell us on a macroscopic level.

40. Experiment: Schrodinger’s Cat Schrodinger’s Cat:

41. Erwin Schrödinger Taylor, ZAIN, Stephen

42. Schrödinger Accomplishments Nobel Prize: 1933 for work in Quantum Mechanics Schrödinger’s equation Worked with Einstein to develop: Schrödinger’s cat thought experiment

43. Schrödinger Experiment Describes how the quantum state of a physical system changes in time. The Schrödinger equation describes time in a way that is inconvenient for relativistic theories.

44. Schrödinger Cat Thought Experiment A thought experiment, often described as a paradox. The thought experiment presents a cat that might be alive or dead, depending on an earlier random event.

45. Atomic Structure II Who: Erwin Schrödinger When: 1930 Where: Austria What: Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom. Why: He was dissatisfied with the quantum condition in Bohr's orbit theory and he believed that atomic spectra should really be determined by some kind of equation.

46. The Neutron

47. Sir James Chadwick October 1891- July 1974

48. Experiments Repeated experiments of the scientists Fredric and Irene Joliot-Curie Looked for a neutral particle instead of particle radiation Experiments were successful Called particle Neutron

49. Theory/ Discovery Discovered the Neutron by basing experiments towards those of Fredric and Irene Joliot-Curie

50. The Neutron Who: James Chadwick When: 1932 Where: England What: Discovered the neutrally charged part of the atom – the neutron. Why: Wanted to determine why atoms were heavier than the protons and electrons combined.