1. PACS 2008 Unit: Atomic Structures Mr. Nylen Pulaski Academy High School 2008

2. The Modern Atom Atom – smallest indivisible particle of matter Atom – smallest indivisible particle of matter Each specific element is made up of the same type of atoms Each specific element is made up of the same type of atoms Every Hydrogen atom has the same number of subatomic particles Every Hydrogen atom has the same number of subatomic particles Every Helium atom has the same number of subatomic particles Every Helium atom has the same number of subatomic particles PACS 2008

3. Atoms Hydrogen AtomOxygen Atom Hydrogen AtomOxygen Atom Element (H) Element (Oxygen) Element (H) Element (Oxygen) Compounds Compounds (H 2 O) PACS 2008

4. Sub-Atomic Particles Atoms are made up of subatomic particles Atoms are made up of subatomic particles Protons Protons Electrons Electrons Neutrons Neutrons All atoms contain subatomic particles All atoms contain subatomic particles A group of atoms making up an element are all IDENTICAL A group of atoms making up an element are all IDENTICAL PACS 2008

5. The main sub-atomic particles ParticleChargeMassSymbolLocation Proton11 amuH +, or +Nucleus Neutron01 amuNucleus Electron0 amue -, or -Outer shell PACS 2008

6. Atomic Mass Mass of the atom – made up mostly of mass of protons and neutrons Mass of the atom – made up mostly of mass of protons and neutrons Measured in Atomic Mass Units Measured in Atomic Mass Units 1 amu = 1/12 the mass of 1 amu = 1/12 the mass of a Carbon-12 atom (the standard for all relative atomic masses) PACS 2008

7. Atomic Mass (A) Since a proton = 1 amu, and a neutron = 1 amu (or u), atomic mass also represents the number of protons and neutrons in the nucleus Since a proton = 1 amu, and a neutron = 1 amu (or u), atomic mass also represents the number of protons and neutrons in the nucleus Electrons have negligible weight and aren’t factored in to atomic mass Electrons have negligible weight and aren’t factored in to atomic mass PACS 2008

8. Atomic Number (Z) Represents the charge in the nucleus Represents the charge in the nucleus For atoms this means Z = the number of protons in the nucleus For atoms this means Z = the number of protons in the nucleus This is what makes an atom of an element different compared to other elements This is what makes an atom of an element different compared to other elements PACS 2008

9. Charting Atoms/Elements Symbol – Accepted letter or letters representing that atom (or element) Symbol – Accepted letter or letters representing that atom (or element) Atomic Number – Directly proportional to number of protons in the nucleus Atomic Number – Directly proportional to number of protons in the nucleus Also represents charge in the nucleus Also represents charge in the nucleus Atomic Mass – Mass of the nucleus Atomic Mass – Mass of the nucleus Remember, electrons are negligible Remember, electrons are negligible Protons + Neutrons Protons + Neutrons PACS 2008

10. Charting Atoms/Elements Number of Protons – Same as atomic number, or usually half of atomic mass Number of Protons – Same as atomic number, or usually half of atomic mass Number of electrons Number of electrons Assuming atom or element has zero charge Assuming atom or element has zero charge # Electrons equal the number of protons # Electrons equal the number of protons Number of neutrons Number of neutrons All the mass of an atom is made up of protons + neutrons All the mass of an atom is made up of protons + neutrons We know the number of protons so we can calculate the number of neutrons We know the number of protons so we can calculate the number of neutrons PACS 2008

11. Page 4-5 Work in small groups Work in small groups PACS 2008

12. Together Notes p. 6 and 7 Notes p. 6 and 7 PACS 2008

13. Isotopes Atoms of the same element (w/same # of protons and same charge) BUT different number of neutrons (therefore different atomic mass) Atoms of the same element (w/same # of protons and same charge) BUT different number of neutrons (therefore different atomic mass) Ex. The 3 naturally occurring isotopes of CARBON Ex. The 3 naturally occurring isotopes of CARBON Carbon 12, Carbon 13, Carbon 14 Carbon 12, Carbon 13, Carbon 14 PACS 2008

14. Carbon 12, 13, and 14 PACS 2008 14

15. Isotopes of Hydrogen Hydrogen usually has 1 proton, and atomic mass of 1 Hydrogen usually has 1 proton, and atomic mass of 1 Isotopes of Hydrogen can have an atomic mass of 2 or 3 Isotopes of Hydrogen can have an atomic mass of 2 or 3 How many protons in these isotopes? How many protons in these isotopes? How many neutrons? How many neutrons? PACS 2008

16. Page 8, Weighted Atomic Mass Atomic mass shown in periodic table is a weighted average of the masses of the naturally occurring isotopes of the element. Atomic mass shown in periodic table is a weighted average of the masses of the naturally occurring isotopes of the element. This is why hydrogen has a mass of 1.00074 This is why hydrogen has a mass of 1.00074 PACS 2008

17. Weighted Atomic Mass You take an exam having three parts. The first multiple choice part is weighted 20%, the second part is weighted 40%, and the third part is weighted 40% You take an exam having three parts. The first multiple choice part is weighted 20%, the second part is weighted 40%, and the third part is weighted 40% A student scores the following A student scores the following PACS 2008 Exam ScoreWeighted Percent Fraction of points earnedOverall Score Part A - 8020% Part B - 7240% Part C - 9440%

18. Weighted Atomic Mass An element has three isotopes (different number of neutrons). What is the weighted atomic mass of the element? An element has three isotopes (different number of neutrons). What is the weighted atomic mass of the element? PACS 2008 Isotope% abundance in nature Fractional AbundanceProduct Carbon 1298.9%12 * (.989) = Carbon 131.05%13 * (.0105) = Carbon 14.05%14 * (.0005) = Weighted Atomic Mass:

19. Weighted Atomic Mass (K) PACS 2008 Isotope% abundance in nature Fractional AbundanceProduct K- 3993.12% K- 406.88% Weighted Atomic Mass:

20. Lab – Isotopes of Pennium PACS 2008

21. Problem Set – Pg. 9 PACS 2008

22. Isotopes = neutrons Ions = electrons PACS 2008

23. Page 10 - Ions Atoms with a net charge. Formed when atoms gain or lose electrons (If an element loses a proton it isn’t the same element anymore!) Atoms with a net charge. Formed when atoms gain or lose electrons (If an element loses a proton it isn’t the same element anymore!) Therefore the number of protons doesn’t equal the number of electrons Therefore the number of protons doesn’t equal the number of electrons PACS 2008

24. Ions - continued If we lose electrons, we become more positive (take away negative charge) If we lose electrons, we become more positive (take away negative charge) If we gain electrons, we become more negative (adding negative charge) If we gain electrons, we become more negative (adding negative charge) If we lose or gain protons, we completely change the atom or element! If we lose or gain protons, we completely change the atom or element! PACS 2008

25. Ions - SUMMARY Never change # of protons Never change # of protons Charge comes from # electrons Charge comes from # electrons If electrons = protons, charge is 0 If electrons = protons, charge is 0 If electrons > protons, charge is negative If electrons > protons, charge is negative If electrons < protons, charge is positive If electrons < protons, charge is positive Neutrons are used to make up difference in atomic mass ONLY (they have no charge) Neutrons are used to make up difference in atomic mass ONLY (they have no charge) PACS 2008

26. Classwork Finish table at bottom of page 10 Finish table at bottom of page 10 PACS 2008

27. Lab - Page 11 - 14 PACS 2008

28. Homework Read section 3-2 in text Read section 3-2 in text Do p. 6-7 At. Structure notes Do p. 6-7 At. Structure notes PACS 2008

29. Ions – Counting neutrons… Bottom of page 10 Bottom of page 10 PACS 2008

30. Isotope Lab PACS 2008

31. Pages 16 – 21 in Notes Answer questions in notes Answer questions in notes Work in computer lab Work in computer lab Work quietly as there is a class next door Work quietly as there is a class next door PACS 2008

32. Models of the atom Dalton’s Indivisible Atom Dalton’s Indivisible Atom J.J. Thomson’s Plum Pudding Model J.J. Thomson’s Plum Pudding Model Rutherford’s Solar System Model Rutherford’s Solar System Model PACS 2008

33. Dalton’s Indivisible Atom Elements consist of tiny particles called “atoms” Elements consist of tiny particles called “atoms” Atoms of different elements are different Atoms of different elements are different Compounds have constant composition because they contain a fixed ratio of atoms Compounds have constant composition because they contain a fixed ratio of atoms tiny, indivisible, indestructible particles tiny, indivisible, indestructible particles PACS 2008

34. J.J. Thomson’s “Plum Pudding” Model Discovered e - in 1897 Discovered e - in 1897 Also called chocolate chip cookie model Also called chocolate chip cookie model How does this differ from what we know about the modern theory of the atom? How does this differ from what we know about the modern theory of the atom? PACS 2008

35. Rutherford’s Atom “Gold foil” experiment “Gold foil” experiment Region of dense charge in center of atom Region of dense charge in center of atom Electrons orbit around this “center” Electrons orbit around this “center” PACS 2008

36. Bohr’s Modern Theory Most accepted during mid/late 1900’s Most accepted during mid/late 1900’s e - actually fill imaginary “shells” e - actually fill imaginary “shells” PACS 2008

37. Wave Mechanical Model Electrons aren’t in “shells”, but rather are in “regions of probability” Electrons aren’t in “shells”, but rather are in “regions of probability” PACS 2008

38. Posters Create a poster outlining one of the models of the atom we talked about Create a poster outlining one of the models of the atom we talked about Dalton Dalton J.J. Thomson J.J. Thomson Rutherford (gold foil experiment or atom) Rutherford (gold foil experiment or atom) Bohr Bohr Wave Mechanical Wave Mechanical Sequential Development of the atom Sequential Development of the atom Poster should contain visuals as well as any other necessary information Poster should contain visuals as well as any other necessary information You will be graded as a group and you will present these to the class You will be graded as a group and you will present these to the class PACS 2008

39. Vocab activity Understanding Understanding Isotopes Isotopes Ions Ions Allotropes Allotropes Atoms Atoms Plum pudding model Plum pudding model Bohr model Bohr model Wave mechanical model Wave mechanical model Gold Foil experiment Gold Foil experiment PACS 2008

40. Create a “puzzle” using Using your topic, create a 9 piece puzzle using definitions about that topic Using your topic, create a 9 piece puzzle using definitions about that topic Example Example Once you have all of your definitions, cut out pieces so they fit together like a puzzle. Once you have all of your definitions, cut out pieces so they fit together like a puzzle. Hide your pieces around the room for another group, bring me the main piece Hide your pieces around the room for another group, bring me the main piece PACS 2008

41. Notes pg 22 Use the timeline on the back of the page to answer questions Use the timeline on the back of the page to answer questions PACS 2008

42. Notes pg. 24-25 PACS 2008

43. Notes pg. 26-27 PACS 2008

44. Problem Set Describe Rutherfords gold foil experiment and write his two conclusions about the atom Describe Rutherfords gold foil experiment and write his two conclusions about the atom PACS 2008

45. Light as a Wave – Electromagnetic Radiation Visible light is energy that travels in the form of an electromagnetic wave Visible light is energy that travels in the form of an electromagnetic wave We can use a sine wave drawing as a model of an electromagnetic wave. We can use a sine wave drawing as a model of an electromagnetic wave. Wavelength = λ Wavelength = λ PACS 2008 crest wavelength crest wavelength

46. Light as a Wave Wave frequency – The number of crests passing a point each second. Units = 1/seconds (Hertz, Hz) Wave frequency – The number of crests passing a point each second. Units = 1/seconds (Hertz, Hz) Wave speed = The speed of all electromagnetic waves in a vacuum is 3x10 8 m/s (This is the speed of light) Wave speed = The speed of all electromagnetic waves in a vacuum is 3x10 8 m/s (This is the speed of light) c = f λ c = f λ c = speed of light, f = frequency, λ = wavelength c = speed of light, f = frequency, λ = wavelength PACS 2008

47. Electromagnetic Spectrum PACS 2008

48. Spectra Looks like a rainbow Looks like a rainbow All frequencies of visible light in one continuous band All frequencies of visible light in one continuous band Produced by passing white light through a prism Produced by passing white light through a prism PACS 2008

49. Bright Line (Emission) Spectra Looks like bright colored lines on a black background Looks like bright colored lines on a black background Only specific frequencies of visible light observed, called Spectral Lines Only specific frequencies of visible light observed, called Spectral Lines Produced by adding energy (by putting in a flame or adding electricity) and viewing light through a prism Produced by adding energy (by putting in a flame or adding electricity) and viewing light through a prism Emission spectra is like a fingerprint for an element Emission spectra is like a fingerprint for an element PACS 2008

50. Emission Spectra PACS 2008

51. Bohr Model of the Atom Applied Quantum Theory to the Atom Energy is absorbed and emitted by atoms in discrete amounts Electrons may only be located in specific orbits Electrons possess definite amounts of energy

52. Bohr Model Electrons arrange themselves in specified energy orbits around nucleus Electrons fill lower energy levels first Arrangement of electrons equals electron configuration

53. Principal Energy Levels K shell (holds 2 electrons) L shell (holds 8 electrons) M shell (holds 18 electrons) N shell (holds 36 electrons) If electrons absorb exactly the difference between 2 orbits, they will “jump up” This is an all or nothing proposition This jumping orbital change causes emission spectra

54. Lab – Spectral Lines PACS 2008

55. Quiz Models of the Atom Models of the Atom PACS 2008

56. Ground State vs. Excited State Ground State The normal energy configuration of electrons Electrons occupy Lowest orbits first Very energetically stable Excited State Electrons absorb energy from external source Electrons jump to higher orbits Higher than normal orbits = excited state

57. Excited State Very unstable Very unstable Electrons want to fall back to ground state Electrons want to fall back to ground state Energy is released when electrons fall back Energy is released when electrons fall back In the form of electromagnetic radiation In the form of electromagnetic radiation These can be in visible These can be in visible range (photons) range (photons) Each jump represents EMR frequence of energy Each jump represents EMR frequence of energy PACS 2008

58. Electron Configurations Add up # electrons Add up # electrons Match to element on periodic table Match to element on periodic table See if electron configuration matches that on periodic table (if so, it is in ground state) See if electron configuration matches that on periodic table (if so, it is in ground state) If no, then it is in excited state If no, then it is in excited state PACS 2008 Example: 12 Mg Example: 12 Mg Ground = 2-8-2 Ground = 2-8-2 Excited = 2-7-3, or 1-8-3, or 1-7-4 Excited = 2-7-3, or 1-8-3, or 1-7-4

59. Practice Zinc = atomic number 30 Zinc = atomic number 30 30 electrons 30 electrons Ground state = 2-8-18-2 Ground state = 2-8-18-2 Electron configuration = 2-5-8 Electron configuration = 2-5-8 15 electrons, atomic number 15 = 15 electrons, atomic number 15 = Element Phosphorous Element Phosphorous Ground state = 2-8-5, so it must be excited Ground state = 2-8-5, so it must be excited Notice: Total number of electrons do not change from ground to excited state Notice: Total number of electrons do not change from ground to excited state PACS 2008

60. More Practice Electron configuration 2-7 Electron configuration 2-7 Number of electrons = Number of electrons = Atomic Number must equal… Atomic Number must equal… Element must be… Element must be… Ground state for element is… Ground state for element is… Does Ground state match 2-7… Does Ground state match 2-7… PACS 2008

61. Try the last 2 on your own PACS 2008

62. Quantum Mechanical Model of the Atom Incorporated findings that electrons behave like waves and particles Incorporated findings that electrons behave like waves and particles Electrons do not move in definite, fixed orbits, they move in areas around the nucleus called orbitals Electrons do not move in definite, fixed orbits, they move in areas around the nucleus called orbitals Orbital = region of space around nucleus where an electron of a certain energy is MOST LIKELY to be found Orbital = region of space around nucleus where an electron of a certain energy is MOST LIKELY to be found PACS 2008

63. Notes pg. 26 Use Text 3-3 as a guide Use Text 3-3 as a guide Part 2: Type of radiation means Tv, microwaves, infrared, etc. Part 2: Type of radiation means Tv, microwaves, infrared, etc. For visible spectrum, list the 7 colors of the rainbow (which has the highest wavelength?) For visible spectrum, list the 7 colors of the rainbow (which has the highest wavelength?) PACS 2008

64. Problem Set Explain the difference between the following in terms of subatomic particles: Explain the difference between the following in terms of subatomic particles: Ions Ions Isotopes Isotopes Atoms Atoms Write a ground state and excited state electron configuration for Bromine Write a ground state and excited state electron configuration for Bromine PACS 2008

65. Review Activity PACS 2008

66. Homework Pg. 28 in notes Pg. 28 in notes PACS 2008