1. Atoms: The Building Blocks of Matter
Unit 2

2. Introduction to the Atom
Modern Atomic Theory
Subatomic Particles
Isotopes
Ions
Essential Standards and objectives:
1.1.1 Analyze the structure of atoms, isotopes, and ions.
1.1.2 Analyze an atom in terms of the location of electrons.
1.1.3Explain the emission of electromagnetic radiation in spectral form in terms
of the Bohr model.
Explain the process of radioactive decay using nuclear equations and half-life.
2.2.5 Analyze quantitatively the composition of a substance. (Introduction to moles)

3. The Atom: Smallest particle of an element that retains the chemical properties of the element.
Essential Questions:
What is an atom?
What is its structure?
What determines properties of an element?

4. Atoms act in orderly, predictable ways.

5. PHET Build an Atom Use this in the search window
Share a computer with a partner
Individual work (write your answers on a separate paper)

6. Explain: How does this graphic demonstrate the
characteristics of an atom?
Make sure that you include each graphic (portions) in your explanation

7. Reading: Cornell notes
Essential questions: What are the characteristics of an atom? In your notes: address both individual atoms and atoms of an element

8. Modern Atomic Theory All matter: Atoms of a given element:
Atoms cannot be created nor destroyed in:
In chemical reactions, atoms are

9. Atomic Theory (cont.) To form compounds: Law of Definite Proportions
Law of Multiple Proportions

10. Summary Table: Atomic Structure- Subatomic Particles
Subatomic Location Charge Mass Importance
Particle AMU

11. Designation of Atomic Structure
Atomic number (Z):
On the Periodic Table:
Mass number (A):

12. Representing atoms
Information from symbols and the Periodic Table

13. What does this symbol tell us? Protons: Neutrons: Electrons:

14. Designations for the Atomic Structure Atomic number (Z):
On the Symbol
On the Periodic Table
Mass number (A): 20 Ca
40.08

15. 31 Ga 69.72 32 Ge 72.61 Gallium Germanium
Review: What is Z? What is A? Determine the number of protons, neutrons, and electrons. 31 Ga
Gallium
69.72 32 Ge
Germanium
72.61

17. Periodic Table: an Important Tool in Chemistry but no set rules for what is included and where16 S
32.06 S 16
32.06
How can we tell which is the atomic number
and the mass number?

18. AMU = relative measurement and used for comparison
Atomic
Mass Unit
AMU
 The “amu” is defined as one twelfth of the mass of an atom of carbon-12  (with 6 protons and 6 neutrons) and has a value of ×10−27 kg.

19. Organization of the Periodic Table
Columns – Groups
All the elements have similar chemical and physical properties
All will chemically react in a similar way
Names of groups
Rows – Periods
Elements have same number of energy levels

20. Isotopes

21. Isotopes - Discovery Education Video

22. Isotopes: Atoms of an element with different masses
Naturally occurring
Some are stable and some are radioactive (unstable)
Isotopes of an element have the same number of ___________ and a different number of ______________.

23. Identifying Isotopes Isotope Notation 1. 2.
On the Periodic Table, the number with the
Decimal point is:

24. Atoms of the Same Element

25. Atoms of the Same Element

26. Atoms of the Same Element

27. Atomic Mass Weighted Average Mass of isotopes
Based on the percentage of each isotope present.

28. Grades are often computed using a weighted average.
Suppose that homework counts 10%, quizzes 20%, Labs 10% and tests 60%.
If:
homework grade is 92
quiz grade is 68
lab grade is 88
test grade is 81
What’s the overall grade?

29. Practice Atomic Structure Atomic Number & Isotopes
Identify the number of proton, neutron, & electrons of an atom of a specific element
Rounding the atomic mass on the Periodic Table gives the mass of the most common isotope
Atomic Number & Isotopes
Correct symbol: A & Z
Complete the table
Complete the questions.

30. Practice: Find the Average Atomic Mass
Nucleus of each atom is represented
Graphic below #4 - explains #5-7
Isotopes: Atomic Number & Mass Number
Determine based on the chart – not the PT
2 Isotope notations
Element – A (X-A) A ZX

31. Find Average Atomic Mass

32. Atomic Number & Isotope

33. Isotopes: Atomic Number & Mass Number
Element
Isotope
Symbol
Atomic
Number Z
Mass A
# of protons
# of neutrons
# of electrons

34. Stable Isotopes - frequency

35. Atom: Scanning Tunneling Microscope

36. Development of the Modern Atomic Model
Here are several models of the atom as they were developed in history:
Development of the Modern Atomic Model

37. Atomic investigation – Discovery Education Video

38. Bohr - Discovery Education Video

39. Quantum Model
Electron Cloud model of the atom

40. Representing atoms with the Bohr model

41. Representing atoms with the Bohr Model

42. Bohr Model – Simplified but Useful Model
Group 1 2
Groups
2-12 13 14 15 16 17 18 P1 P2 P3

43. Bohr Model & the Periodic Table Making Conclusions
Compare and Contrast
Why are elements placed in a group (column)?
Why are elements placed in a period (row?)

44. Changing An Atom
Changing an Atom

45. Ions
Atoms can lose or gain electrons when bonding to make ionic compounds
We keep track of the number of electrons that can be lost or gained with oxidation numbers (also known as charges)
Ions are charged particles –when an atom has too many or too few electrons to be neutral
No change to the nucleus
Proton and neutrons stay the same number.

46. Ions – Charged Particles
7. When atoms of elements form ions (__________ __________, they must either __________ or _______ valence electrons.
Gain/lose? Charge Ion type?
Metals
Non-metals 46 46

47. Why are ions important?
The ___________________ charged particles are like a magnet.
Therefore, they are strongly held together in an ______________ _____________ forming an _____ ________________. 47

48. Representing atoms with the Bohr Model

49. Ions Lithium atom - Lithium ion Ion Symbol p+ p+ nº nº e- e-
Fluorine atom Fluorine ion 49 49

50. Ions and Charge Net electric charge
Note change 8 50 50

51. Ions and Charges for Representative Elements (Oxidation number keep track of electrons)
Group 1 2 13 14 15 16 17
Group 18 51

52. Ion Making
Holy Molee Song 52 52

53. Making an ion of an alkali metal, First column in the periodic chart,
Leaves all the ions
with a plus one
charge
And they’re all a
whole lot smaller
than they were
before. 53 53

54. Loses 2 electrons easily, So their ions all have a plus 2 charge,
Second column over,
Alkaline earths,
Loses 2 electrons easily,
So their ions all have
a plus 2 charge,
And they’re smaller
than their neighbors
to the left. 54 54

55. 55 55

56. It’d like to have removed. When they are gone, it has a +3 charge,
Next door, aluminum,
the 3rd step over
has 3 electrons
It’d like to have removed.
When they are gone, it
has a +3 charge,
And, by gosh!, It’s even
smaller than the
“lefter” two. 56 56

57. But add one electron To the halogen group, So they all have a
Negative one charge.
They get 8x bigger than
They were before.
Puffed up, very large. 57 57

58. 58 58

59. complete electron shell. Thus, minus 2 is their ionic charge.
Sulfur and oxygen
need 2 electrons to
give each a full and
complete electron shell.
Thus, minus 2 is their
ionic charge.
And they’re a little larger
Than the “Hal-ions”. 59 59

60. Add three electrons to the nitrogen group.
So that group has a triple minus charge.
And the pattern we see makes it very clear.
Negative ions are large! 60 60

61. 61 61

62. Mole
Resources for students

63. Nuclear Chemistry

64. Neutron to Proton Ratio

65. Types of Radiation

66. Alpha Decay

67. Beta decay

68. Gamma Decay

69. Radiation Strength

70. Nuclear Equations Practice Website
11H + 94Be ---> 63Li + ?
2713Al + 42He ---> 3015P + ?
2412Mg  2412Mg + ?
23892U  23490Th + ?
146C  0-1e + ?
23994Pu + 42He  24296Cm + ?
Nuclear Equations Practice Website

71. Half-life Measure of Radioactive decay rate.
Measured as the time it takes for ½ of a sample of radioisotope’s nuclei to decay into its products.

72. Half Life Decay of a radioisotope Number of Half-Lives Elapsed time
Amount remaining
100 g 1
1.5 year
50 g 2
3 years
25 g 3
4.5 years
12.5 g

73. Half Life Problems
How much of a 100g sample of an unstable isotope remains after 25 years if the half life is 5 years?
3.1 g

74. Half Life Problems
How much of a 60g sample of an unstable isotope remains after 2 days if the half life is 12 hours?
7.5 g

75. Half Life Problems
How much of a 20 g sample of an unstable isotope remains after 6 sec if the half life is 0.5?
0.005 g

76. Atomic Nucleus (also known as nuclide)
Mass
Energy
Volume

77. Radioactive Isotopes
A radioactive isotope has an unstable nucleus that undergoes spontaneous changes.
Emits particles and energy
Transmutates into another element

78. Particles emitted from a radioactive isotope
Type Symbol Charge Mass

79. Nuclear reactions
Total number of atomic numbers and the total mass numbers must be equal on both sides of the equation. Examples:

80. Radioactive decay
No 2 radioactive isotopes decay at the same rate. Therefore, decay rate can be used to identify the isotope. Decay is measured by half life.

81. Fission and Fusion

82. Origins of Element

83. Got Calcium Where are most elements created?
When was H and He created?
What elements are made by small stars?
What additional elements are made by large stars?
What elements are made by supernovae (large exploding stars)?

84. Teachers' Domain: The Origin of the Elements

85. Teachers' Domain: The Elements: Forged in Stars