1. BELLRINGER 11/2/15
What is an electron? Where is it located? How can you tell from the periodic table how many electrons in an atom? GET YOUR NOTEBOOKS.

2. Orbitals...

3. Electrons are part of what
makes an atom an atom

4. Electrons are part of what
makes an atom an atom
But where exactly are the
electrons inside an atom?
atom

5. where there is a high probability
Orbitals (AKA Shells)
are areas within atoms
where there is a high probability
of finding electrons.

6. Knowing how electrons are
arranged in an atom is
important
because that governs
how atoms interact
with each other

7. Knowing how electrons are
arranged in an atom is
important
because that governs
how atoms interact
with each other

8. Knowing how electrons are
arranged in an atom is
important
because that governs
how atoms interact
with each other

9. Knowing how electrons are
arranged in an atom is
important
because that governs
how atoms interact
with each other

10. Knowing how electrons are
arranged in an atom is
important
because that governs
how atoms interact
with each other

11. Knowing how electrons are
arranged in an atom is
important
because that governs
how atoms interact
with each other

12. Knowing how electrons are
arranged in an atom is
important
because that governs
how atoms interact
with each other

13. Let’s say you have a
room with flies flying
around in it

14. The flies are not just
anywhere in the room.
They are inside boxes in
the room.

15. You know where the
boxes are, and you
know the flies are
inside the boxes, but…

16. you don’t know exactly
where the flies are
inside the boxes

17. The flies are electrons
The room is an atom
The flies are electrons
The boxes are orbitals

18. The flies are electrons
The room is an atom
The flies are electrons
The boxes are orbitals

19. Science has determined where the
orbitals are inside an atom, but it
is never known precisely where the
electrons are inside the orbitals

21. Hey,
where
am I?

22. So what are the
sizes and shapes
of orbitals?

23. The area where an electron can be found, the orbital,
is defined mathematically,
but we can see it as a specific shape
in 3-dimensional space…

24. z y x

25. z y
The 3 axes represent
3-dimensional space x

26. z y x For this presentation, the nucleus of the atom is at
the center of the three axes. x

27. The “1s” orbital is a
sphere, centered
around the nucleus

30. The 2s orbital is also
a sphere.

31. The 2s electrons have a
higher energy than the 1s
electrons. Therefore, the 2s
electrons are generally more
distant from the nucleus,
making the 2s orbital larger
than the 1s orbital.

32. 1s orbital

33. 2s orbital

34. Don’t forget:
an orbital is the shape of the
space where there is a high
probability of finding electrons

35. Don’t forget:
an orbital is the shape of the
space where there is a high
probability of finding electrons
The s orbitals are spheres

36. There are three
2p orbitals

37. The three 2p orbitals
are oriented
perpendicular
to each other

38. z
This is
one 2p orbital
(2py) y x

39. z
another 2p orbital
(2px) y x

40. z
the third 2p orbital
(2pz) y x

41. Don’t forget:
an orbital is the shape of the
space where there is a high
probability of finding electrons

42. This is the shape of p orbitals
Don’t forget:
an orbital is the shape of the
space where there is a high
probability of finding electrons
This is the shape of p orbitals

43. z y x

44. z
2px y x

45. z
2px and 2pz y x

46. The three 2p orbitals, 2px, 2py, 2pz

47. once the
1s orbital
is filled,

48. the 2s orbital
begins to fill

49. once the 2s
orbital is
filled,

50. the 2p orbitals
begin to fill

51. each 2p orbital
intersects the
2s orbital and
the 1s orbital

52. each 2p orbital
gets one electron
before pairing begins

53. once each 2p orbital
is filled with a pair
of electrons, then

54. the 3s orbital
gets the next
two electrons

55. the 3s electrons
have a higher energy
than 1s, 2s, or 2p
electrons,

56. so 3s electrons are
generally found
further from the
nucleus than 1s,
2s, or 2p electrons

57. d Orbitals
d sublevel has 5 orbitals

58. The shapes and labels of the five 3d orbitals.

59. Quantum Mechanics http://www. meta-synthesis
Better than any previous model, quantum mechanics does explain how the atom behaves.
Quantum mechanics treats electrons not as particles, but more as waves (like light waves) which can gain or lose energy.
But they can’t gain or lose just any amount of energy. They gain or lose a “quantum” of energy.
A quantum is just an amount of energy that the electron needs to gain (or lose) to move to the next energy level.
In this case it is losing the energy and dropping a level.

60. Atomic Orbitals http://milesmathis.com/bohr2.jpg
Much like the Bohr model, the energy levels in quantum mechanics describe locations where you are likely to find an electron.
Remember that orbitals are “geometric shapes” around the nucleus where electrons are found.
Quantum mechanics calculates the probabilities where you are “likely” to find electrons.
An old Bohr??
Mwwhaha!

61. Atomic Orbitals http://courses. chem. psu. edu/chem210/quantum/quantum
Of course, you could find an electron anywhere if you looked hard enough.
So scientists agreed to limit these calculations to locations where there was at least a 90% chance of finding an electron.
Think of orbitals  as sort of a "border” for spaces around the nucleus inside which electrons are allowed. No more than 2 electrons can ever be in 1 orbital. The orbital just defines an “area” where you can find an electron.
What is the chance of finding an electron in the nucleus? Yes, of course, it’s zero. There aren’t any electrons in the nucleus.

62. Energy Levels http://www.chem4kids.com/files/art/elem_pertable2.gif
Quantum mechanics has a principal quantum number. It is represented by a little n. It represents the “energy level” similar to Bohr’s model.
n=1 describes the first energy level
n=2 describes the second energy level
Etc.
Each energy level represents a period or row on the periodic table. It’s amazing how all this stuff just “fits” together.
Red n = 1
Orange n = 2
Yellow n = 3
Green n = 4
Blue n = 5
Indigo n = 6
Violet n = 7

63. Sub-levels = Specific Atomic Orbitals
Each energy level has 1 or more “sub-levels” which describe the specific “atomic orbitals” for that level.
n = 1 has 1 sub-level (the “s” orbital)
n = 2 has 2 sub-levels (“s” and “p”)
n = 3 has 3 sub-levels (“s”, “p” and “d”)
n = 4 has 4 sub-levels (“s”, “p”, “d” and “f”)
There are 4 types of atomic orbitals:
s, p, d and f
Each of these sub-levels represent the blocks on the periodic table.
Blue = s block
Yellow = p block
Red = d block
Green = f block

64. Orbitals http://media-2. web. britannica
In the s block, electrons are going into s orbitals.
In the p block, the s orbitals are full. New electrons are going into the p orbitals.
In the d block, the s and p orbitals are full. New electrons are going into the d orbitals.
What about the f block?

65. Objective C Complete the chart in your notes as we discuss this.
Energy Level
Sub-levels
Total Orbitals
Total Electrons
Total Electrons per Level
n = 1 s
1 (1s orbital) 2
n = 2 p
1 (2s orbital)
3 (2p orbitals) 6 8
n = 3 d
1 (3s orbital)
3 (3p orbitals)
5 (3d orbitals) 10 18
n = 4 f
1 (4s orbital)
3 (4p orbitals)
5 (4d orbitals)
7 (4f orbitals) 14 32
Complete the chart in your notes as we discuss this.
The first level (n=1) has an s orbital. It has only 1. There are no other orbitals in the first energy level.
We call this orbital the 1s orbital.

66. Where are these Orbitals. http://www. biosulf2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 5d 6p 7s 6d 7p 4f 5f

67. Electron Configurations
What do I mean by “electron configuration?”
The electron configuration is the specific way in which the atomic orbitals are filled.
Think of it as being similar to your address. The electron configuration tells me where all the electrons “live.”

68. Rules for Electon Configurations https://teach. lanecc
In order to write an electron configuration, we need to know the RULES.
3 rules govern electron configurations.
Aufbau Principle
Pauli Exclusion Principle
Hund’s Rule
Using the orbital filling diagram at the right will help you figure out HOW to write them
Start with the 1s orbital. Fill each orbital completely and then go to the next one, until all of the elements have been acounted for.

69. Fill Lower Energy Orbitals FIRST http://www. meta-synthesis
Each line represents an orbital.
1 (s), 3 (p), 5 (d), 7 (f)
The Aufbau Principle states that electrons enter the lowest energy orbitals first.
The lower the principal quantum number (n) the lower the energy.
Within an energy level, s orbitals are the lowest energy, followed by p, d and then f. F orbitals are the highest energy for that level.
High Energy
Low Energy

70. No more than 2 Electrons in Any Orbital…ever. http://www. fnal
The next rule is the Pauli Exclusion Principal.
The Pauli Exclusion Principle states that an atomic orbital may have up to 2 electrons and then it is full.
The spins have to be paired.
We usually represent this with an up arrow and a down arrow.
Since there is only 1 s orbital per energy level, only 2 electrons fill that orbital.
Wolfgang Pauli, yet another German Nobel Prize winner
Quantum numbers describe an electrons position, and no 2 electrons can have the exact same quantum numbers. Because of that, electrons must have opposite spins from each other in order to “share” the same orbital.

71. Hund’s Rule http://intro. chem. okstate
Hunds Rule states that when you get to degenerate orbitals, you fill them all half way first, and then you start pairing up the electrons.
What are degenerate orbitals?
Degenerate means they have the same energy.
So, the 3 p orbitals on each level are degenerate, because they all have the same energy.
Similarly, the d and f orbitals are degenerate too.
Don’t pair up the 2p electrons until all 3 orbitals are half full.

72. Objective D
NOW that we know the rules, we can try to write some electron configurations.
Remember to use your orbital filling guide to determine WHICH orbital comes next.
Lets write some electron configurations for the first few elements, and let’s start with hydrogen.

73. Electron Configurations
Element
Configuration
H Z=1
1s1
He Z=2
1s2
Li Z=3
1s22s1
Be Z=4
1s22s2
B Z=5
1s22s22p1
C Z=6
1s22s22p2
N Z=7
1s22s22p3
O Z=8
1s22s22p4
F Z=9
1s22s22p5
Ne Z=10
1s22s22p6
(2p is now full)
Na Z=11
1s22s22p63s1
Cl Z=17
1s22s22p63s23p5
K Z=19
1s22s22p63s23p64s1
Sc Z=21
1s22s22p63s23p64s23d1
Fe Z=26
1s22s22p63s23p64s23d6
Br Z=35
1s22s22p63s23p64s23d104p5
Note that all the numbers in the electron configuration add up to the atomic number for that element. Ex: for Ne (Z=10), = 10

74. Objective D
One last thing. Look at the previous slide and look at just hydrogen, lithium, sodium and potassium.
Notice their electron configurations. Do you see any similarities?
Since H and Li and Na and K are all in Group 1A, they all have a similar ending. (s1)

75. Electron Configurations
Element
Configuration
H Z=1
1s1
Li Z=3
1s22s1
Na Z=11
1s22s22p63s1
K Z=19
1s22s22p63s23p64s1
This similar configuration causes them to behave the same chemically.
It’s for that reason they are in the same family or group on the periodic table.
Each group will have the same ending configuration, in this case something that ends in s1.

76. What does that have to do with anything??

77. depend on how the electrons are arranged in each atom
the billions of interactions of atoms
constantly going on around you
depend on how the electrons
are arranged in each atom

78. (its orbitals) the arrangement of an atom’s electrons
the billions of interactions of atoms
constantly going on around you
depend on how the electrons
are arranged in each atom
the arrangement of an atom’s electrons
(its orbitals)
govern how that atom will interact
with other atoms

79. If atoms did not interact with each other,
the billions of interactions of atoms
constantly going on around you
depend on how the electrons
are arranged in each atom
the arrangement of an atom’s electrons
(its orbitals)
govern how that atom will interact
with other atoms
If atoms did not interact with each other,
you would not be sitting here reading this

80. a specific organization allowing for intersting
An interesting place
where electrons have
a specific organization
within atoms,
allowing for intersting
atom interactions

81. (does not actually exist) An interesting place where electrons have
a specific organization
within atoms,
allowing for intersting
atom interactions
Not an interesting place,
where electrons have
no specific organization
within atoms,
where atoms wander
aimlessly about