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  1. Chemistry: Atomic Structure by Tim F. Rowbotham - modified in 2008 , 2011

  2. Pre-Assessment Questions • Ready your remote

  3. Which of the following is the most accurate model of the structure of an atom? • Tiny solid sphere • Tiny solar system • Spherical Cloud • Chocolate chip cookie

  4. Which of the following is not a particle found in an atom? • Neutron • Electron • Proton • Cathode

  5. The Mass Number of an atom is the total number of what? • Protons & Electron • Protons & Neutrons • Neutrons & Electrons • Protons, Neutrons & Electrons

  6. The Atomic Number of an atom is the total number of what in an atom? • Protons • Protons & Electrons • Protons, Neutrons & Electrons • Chemical Bonds

  7. Which of the following has a negative charge? • Proton • Neutron • Electron • Positron

  8. Atomic Structure Notes • PAGE 1

  9. Chemistry: Atomic Structure Created in 2008 by Tim F. Rowbotham

  10. Atomic History • Ancient Greeks thought there were only 4 elements: earth, air, fire, & water. • All matter, they thought, included one or more of these elements.

  11. Atomic History • Democritus (440 BC) was the first to challenge this idea. • He thought that matter could eventually be divided up into its smallest piece. This piece he theorized, he called atomos, which means “indivisible.”

  12. Atomic Theory • In 1802, John Dalton (a British school teacher) proposed an atomic theory, which included several ideas. • Dalton’s Atomic Theory VIDEO CLIP

  13. Dalton’s Atomic Theory • Atoms are tiny, invisible spheres impossible to break. • Atoms of different elements are different and have specific masses. • Atoms can combine in exact ratios to form compounds.

  14. Thompson’s Model • In the late 1800s, JJ Thompson discovered that there were negatively charged particles which he called electrons. He pictured the atom as a ball of positive charge with negatively charged electrons floating in it. • VIDEO CLIPS: • THOMSON , THOMSON feat Eminem

  15. Rutherford’s Model • In 1911, Ernest Rutherford determined that the center of the atom had a positive charge. • This positively charged center was called the nucleus. • RUTHERFORD • Rutherford Gold Foil Experiment - Backstage Science

  16. Chadwick’s Discovery • James Chadwick discovered that the nucleus also held particles with no charge, which he called neutrons. • The positively charged particles in the nucleus were called protons.

  17. The Bohr Model • Neils Bohr hypothesized that the atom was like a tiny solarsystem, with electrons circling the nucleus in well defined orbits like planets • The speculated paths of the electrons were called orbitals, shells, or energylevels.

  18. Modern Atomic Theory • It was later discovered that electrons do not have well defined orbits, but rather move much more haphazardly. • In fact, Heisenberg determined that we can not simultaneously know the location and velocity of an electron!!! • Uncertainty principle 1 • Uncertainty Principle 2 • Schrodinger’s Cat – Big Bang Theory

  19. Electron Cloud Model • However, each electron has certain regions where it is more likely to be found. • The electroncloud describes the “blur” created from the more frequent movement of electrons through these regions.

  20. Electron Cloud Model • The electron cloud is a spherical cloud around the nucleus that shows were an electron is most likely to be. • It is the most accurate model of an atom, but not the most useful.

  21. Electron Cloud Model The denser areas are where the electrons are MOST likely to be. Atomic Model Video Clip

  22. Learning Checks • Ready your remote

  23. Which of the following is the most accurate model of the structure of an atom? • Spherical Cloud • Tiny solid sphere • Tiny solar system • Chocolate chip cookie

  24. Which scientist is considered the Father of Chemistry because of his atomic theory? • J.J. Thomson • Neils Bohr • John Dalton • James Chadwick

  25. Learning Checks • Return your remote • Read & Complete p.10 – 11 “Particles of Matter”

  26. Review Questions • Ready your remote

  27. Which part of Dalton’s Atomic theory was later found out to be incorrect? • Atoms of different elements are different • Atoms are tiny unbreakable spheres • Atoms combine in specific ratios • Different atoms have different masses

  28. Which of the following is the most accurate model of the structure of an atom? • Tiny solid sphere • Tiny solar system • Spherical Cloud • Chocolate chip cookie

  29. Atomic Structure Notes • PAGE 3

  30. Subatomic Particles • An atom consists of a positive core called a nucleus, which contains positive protons and neutral neutrons. • This nucleus is surrounded by a cloud of negatively charged electrons.

  31. The Charge of Atoms • Alone, atoms are electrically neutral. • This means that they have no OVERALL electric charge. • The positive charge of an atom is exactly equal to its negative charge.

  32. The Negative of Atoms • The extremely rapid movement of electrons forms the cloud of negative charge outside an atom’s nucleus. • Each electron has a charge of -1.

  33. The Positive of Atoms • The nucleus of an atom holds a positive charge due to the presence of protons. • Each proton has a charge exactly opposite to that of an electron equaling +1.

  34. The Nucleus of an Atom • The nucleus of an atom contains the bulk of the mass of the atom. • In it are positively charged protons and neutrons, which have NO charge.

  35. Atomic Mass Unit • Because atoms are so small, we use a special unit of measurement called an atomicmassunit. • An atomic mass unit is really equal to about 1.66 x 10-27 kg.

  36. Masses of Subatomic Particles • A Proton’s mass = 1 a.m.u. • A Neutron’s mass = 1 a.m.u. • A Electron’s mass = 0 a.m.u.* *An electron has a mass of 1/1836th of a proton (which is relatively insignificant)

  37. Charges of Subatomic Particles • A Proton’s charge = +1 • A Neutron’s charge = 0 • A Electron’s charge = -1

  38. COMPLETE THIS TABLE

  39. COMPLETE THIS TABLE

  40. Exit Questions Ready your remote

  41. Which of the following is the most accurate model of the structure of an atom? • Tiny solid sphere • Tiny solar system • Spherical electron cloud • Chocolate chip cookie

  42. Which of the following has a positive charge? • Proton • Neutron • Electron • Beta particle

  43. Which of the following has a mass of 1 amu? • Proton • Neutron • Electron • Proton & Neutron

  44. Modern Atomic Theory Return your remote Atom – Bill Nye VIDEO Read & complete PACKET pages 12-13“What is Matter?”

  45. Entrance Review Questions • Ready your remote

  46. Which of the following has a mass of 1 amu? • Proton • Neutron • Electron • Proton & Neutron

  47. Which of the following has no considerable mass (effectively making it 0 amu? • Proton • Neutron • Electron • Proton & Neutron

  48. Which subatomic particle has a negative charge? • Proton • Neutron • Electron • Positron

  49. Which subatomic particle has a positive charge? • Proton • Neutron • Electron • Beta particle

  50. Which subatomic particle has no overall charge? • Proton • Neutron • Electron • Quark