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Chapter 2

Chapter 2. Atoms, Molecules, & Ions. Atomic Theory. Elements composed of atoms Atoms can’t be changed Compounds of multiple atoms John Dalton. Conservation of Mass. In ordinary chemical reactions, matter can be neither created nor destroyed. Constant Composition.

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Chapter 2

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  1. Chapter 2 • Atoms, Molecules, & Ions

  2. Atomic Theory • Elements composed of atoms • Atoms can’t be changed • Compounds of multiple atoms • John Dalton

  3. Conservation of Mass • In ordinary chemical reactions, matter can be neither created nor destroyed

  4. Constant Composition • Compounds contain elements that are always in the same proportions

  5. Multiple Proportions

  6. The elements making up a compound will form whole number ratios

  7. Atom • The smallest particle that an element can be broken down into and still maintain the properties of the element

  8. Nuclear Atom • Proved by Rutherford & Bohr in the famous gold foil experiments

  9. Atomic Composition • Proton: in the nucleus • Neutron: in the nucleus • Electron: outside the nucleus

  10. Proton • In Nucleus • +1 charge • About 1 amu in mass

  11. Neutron • In nucleus • Neutral in charge • Mass is about 1 amu

  12. Electron • Outside the nucleus • -1 in charge • Negligible mass about 1/2000 amu

  13. Electron Charge • Determined by Robert Milliken in the famous oil droplet experiment

  14. Drill: Convert: 1) 23 cm/ms to km/ns 2) 56 mg/nL to kg/ML

  15. Atomic Number • The number of protons in an element • Z number

  16. Mass Number • The number of protons and neutrons in an atom • A - number

  17. Nuclear Symbol • A 4 • X He • Z 2

  18. Isotopes • Atoms that contain the same number of protons, but different number of neutrons • Z constant, A variable

  19. Atomic Mass • The weighted average mass of all the isotopes of an element • average of relative abundance x mass number for each isotope

  20. Periodic Table • Graphic representation of all the elements indicating size, charge, electronic structure, & reactivity

  21. Periods • Rows which indicate energy level or shell or size of the atoms

  22. Groups or Families • Columns which indicate the number of electrons in the outermost energy level determining charge & reactivity

  23. Metals • Left three quarters of the chart • Lose electrons • Become positive

  24. Nonmetals • Upper right portion • Gain, lose, or share electrons when they react

  25. Metalloids • Along the stair-stepped line from B to At • Share properties of metals & nonmetals

  26. Radioactivity • The spontaneous breakdown of an unstable nucleus

  27. Radioactive Decay • Alpha radiation • Beta radiation • Gamma radiation

  28. Alpha Particle • Helium nucleus • 2 protons & two neutrons • mass = 4 & charge = +2 • Low penetrating power

  29. Beta Particle • High speed electron • Mass = 0 & charge = -1 • Medium penetrating power

  30. Gamma Rays • High energy electromagnetic wave • No mass or charge • Very high penetrating power

  31. Drill: • List & describe each of the three radioactive particles

  32. Compound • A group of atoms that are chemically combined

  33. Molecule • A compound that can exist by itself

  34. Diatomic Molecule • Two atoms of the same element that are chemically combined • Cl2, F2, O2

  35. Ion • Charged Particle • Cl-1

  36. Polyatomic Ion • A group of atoms chemically combined that together has a charge • SO4-2

  37. Binary Compound • A compound made up of two elements in any ratio • NaCl • Mg3P2

  38. Chemical Formula • A formula that shows the number and kinds of atoms in a compound • CaCO3

  39. Molecular Formula • A formula that shows the number and kinds of atoms in a molecule • C6H12O6

  40. Atomic Structure • List & describe the three subatomic particles

  41. Atomic Structure • Fill in the Chart: • Isotope protons neutrons electrons • U-235 - - - • - 56 80 - • - - 14 13

  42. Calculate the atomic mass of the element made up of the following isotopes:99.50 % H-10.30 % H-20.20 % H-3

  43. Calculate the atomic mass of the element made up of the following isotopes:5.0 % Pu-242, 5.0 % Pu-24380.0 % Pu-244, & 10.0 % Pu-245

  44. Determine the number of of atoms in each compound • C6H12O6 NaNO3 • H3PO4 Al2(SO4)3

  45. List & describe each of the three types of radiation

  46. Chapter 2 General • Define all the Key Terms on page 48

  47. Nuclear Symbols • Work problems: • 11 - 18 • on page 50

  48. Nuclear Symbols • Work problems: • 19 - 24 • on page 50

  49. Elements & PT • Work problems: • 27 - 88 • on page 51

  50. Nomenclature • Work problems: • 45 - 48 • on page 51

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