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Atomic Number

Atomic Number. Number of Protons. Always an integer!. Mass Number. Number of Protons + Neutrons. Always an integer!. 12 C. Left Superscript = mass number. 6. 12 C. Left Subscript = atomic number. 6. 80 Br. 35. 35. Atomic Number = ?. 20 Ne. 10. 20. Mass Number = ?. 27 Al. 13.

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Atomic Number

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  1. Atomic Number Number of Protons Always an integer!

  2. Mass Number Number of Protons + Neutrons Always an integer!

  3. 12C Left Superscript = mass number 6

  4. 12C Left Subscript = atomic number 6

  5. 80Br 35 35 Atomic Number = ?

  6. 20Ne 10 20 Mass Number = ?

  7. 27Al 13 27 Mass Number = ?

  8. 40Ca 20 20 Atomic Number = ?

  9. # of electrons in a neutral atom? Neutral atoms have the same number of electrons and protons.

  10. Isotope Same # of protons, different # of neutrons Same atomic #, different mass # Atoms of the same element with a different # of neutrons 12 14 6C and 6C

  11. Characteristics of Proton Charge = +1, mass = 1 amu, location = inside nucleus

  12. Characteristics of Neutron Charge = 0, mass = 1 amu, location = inside nucleus

  13. Characteristics of Electron Charge = -1, mass = 1/1836 amu or 0.0005 amu, location = outside nucleus

  14. Summary of facts for subatomic particles

  15. Ion An atom that has gained or lost electrons & so carries charge

  16. Positive Ion An atom that has LOST electrons

  17. Negative Ion An atom that has GAINED electrons

  18. Charge # protons - # electrons

  19. Nucleons Protons & Neutrons

  20. atom Smallest bit of an element that retains the properties of the element.

  21. atom Smallest bit of an element that can participate in a chemical reaction.

  22. # of neutrons Mass number – atomic number Subtract the atomic number FROM the mass number!

  23. 14C 6 8 neutrons 6 protons 6 electrons # of neutrons = ? # of protons = ? # of electrons = ?

  24. 9Be 4 5 neutrons 4 protons 4 electrons # of neutrons = ? # of protons = ? # of electrons = ?

  25. 40Ar 18 22 neutrons 18 protons 18 electrons # of neutrons = ? # of protons = ? # of electrons = ?

  26. 15N 7 8 neutrons 7 protons 7 electrons # of neutrons = ? # of protons = ? # of electrons = ?

  27. 24Mg 2+ Right superscript = charge 12

  28. 15N -3 7 8 neutrons 7 protons 10 electrons (gained 3) # of neutrons = ? # of protons = ? # of electrons = ?

  29. 19F -1 9 10 neutrons 9 protons 10 electrons (gained 1) # of neutrons = ? # of protons = ? # of electrons = ?

  30. 16O -2 8 8 neutrons 8 protons 10 electrons (gained 2) # of neutrons = ? # of protons = ? # of electrons = ?

  31. 23Na +1 11 12 neutrons 11 protons 10 electrons (lost 1) # of neutrons = ? # of protons = ? # of electrons = ?

  32. 24Mg +2 12 12 neutrons 12 protons 10 electrons (lost 2) # of neutrons = ? # of protons = ? # of electrons = ?

  33. 27Al +3 13 14 neutrons 13 protons 10 electrons (lost 3) # of neutrons = ? # of protons = ? # of electrons = ?

  34. Nuclear Charge Charge on the nucleus only. Does not include the electrons. Always positive. Equals the number of protons. Equals the atomic number.

  35. Cation Positive ion

  36. Anion Negative ion

  37. Dalton’s Model Billiard Ball Model Solid Indivisible Homogeneous

  38. Dalton’s model All matter is composed of atoms. Atoms of a given element are identical, atoms of different elements are different.* Atoms cannot be subdivided, created, or destroyed.* Atoms of different elements combine in small whole number ratios to make compounds. In chemical reactions, atoms are rearranged.

  39. Thomson’s Model Plum Pudding Model + - Solid Divisible Inhomogeneous: contain charges! Electrons are particles! - - + + + - + -

  40. Deflection in magnetic field Deflection of cathode ray No deflection in field free region Deflection in electrostatic field

  41. Thomson’s model Thomson gets credit for discovering electron because he got the first “numbers” – he found the charge-to-mass ratio of the electron.

  42. Rutherford’s Model Nuclear Model - Mostly empty space Divisible Inhomogeneous Contains a small, dense positive nucleus + - -

  43. Rutherford’s model Nuclear Model

  44. Rutherford’s Experiment Shot αlpha particles at gold foil. Most went through, so most of the atom is empty space. Some deflected back by small dense positive nucleus.

  45. A very small percent of the alpha particles deflected back: Evidence for a small, dense, positive nucleus. Most of the alpha particles went through so most of the atom is empty space Rutherford’s Experiment

  46. Bohr’s Model Shell Model

  47. Bohr’s Model Shell Model Electron is still a particle. Quantized energy levels. Electrons move on 3-D spherical orbits.

  48. Bohr Configurations Bohr configurations are “irregular” because the Bohr model is incorrect. You cannot predict them for the larger atoms, even if you know the maximum capacities of each orbit. In the NYS Reference Tables!

  49. Valence electrons are in outermost orbit Bohr Diagram 16 p Sulfur: 2-8-6

  50. Sulfur: 2-8-6 3 occupied levels but only two completely occupied levels. Read question with care! Bohr Configuration Maximum Capacity of Orbits

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