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What does the atom really look like Do the electrons really orbit like the planets

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No. The negative charge the electrons carry looks smeared out or like a cloud. ... Now suppose that we add a third electron where will the three of them end up? ... – PowerPoint PPT presentation

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Title: What does the atom really look like Do the electrons really orbit like the planets


1
The Modern Quantum Description of the Atom
What does the atom really look like? Do the
electrons really orbit like the planets?
No. The negative charge the electrons carry
looks smeared outor like a cloud.
2
Another possible formation (note this is ONE
electron)
3
Other possible configurations (or symmetries)
4
These symmetries are responsible for the symmetry
in the bonding of solids!
5
Summary Atomic models
Greek Jellium Planetary Bohr (Quantum) Modern
Quantum
6
Scientific Notation
How do we write 1,000,000,000,000,000,000 in a
more compact form?
1,000,000,000,000,000,000
There are 18 zeros
We write this as 1 x 1018
7
How do we write 1,200,000,000,000,000,000?
Again there are 18 spots after the first number,
but we have to account for the 2.
Answer 1.2 x 1018
8
What is (1.82 x 1012) x (3.87 x 109)?
Step 1 group the numbers as follows (1.82 x
3.87) x (1012 x 109)
Step 2 multiply these 7.04
Step 3 add the exponents of the 10s 21
Step 4 Write the result 7.04 x 1021
9
What is (2.4 x 1020) / (1.6 x 1011)?
Step 1 (Group) (2.4/1.6) x (1020 / 1011)

Step 2 (Divide numbers) 1.5
Step 3 SUBTRACT exponents 9
Step 4 Write in scientific notation
1.5 x 109
10
What is 0.0000000000005 in scientific notation?
There are 13 digits. Thus we can write this as
5.0 x 10-13
11
What is (3.0 x 1012) x (2.0 x 10-4)?
6.0 x 108
What is (6.0 x 104) / (3.0 x 10-3)?
2.0 x 107
And now to use scientific notation …
12
Charges Revisited
1 It comes it two types positive and
negative. 2 Charge is conserved. 3 Like
charges repel opposites attract. 4 It only
comes in discrete amounts (the amount that comes
with an electron).
13
Materials
Conductors materials where the electrons are
free to move through the material. Examples
include metals (like wires), salt water, etc.
Insulators Electron are NOT free to move through
the material. Examples include rubber, plastic,
wood, coatings on electrical cords, etc.
14
Conductors
Describe the forces between the two charges.
Since unlike charges attract, the electrostatic
force will try to pull them together.
How will the charges MOVE if the material is an
insulator?
They will NOT movethe electrons cant move in an
insulating material.
15
How will the charges move if the material is a
conductor?
They will move towards one another.
16
Describe the force between two negative charges
placed in a conducting material.
Like charges repel so the two charges will repel
one another.
How will the charges MOVE?
They will move away from one another.
17
Where will the charges end up?
18
WHY do the charges end up in this configuration??
They want to maximize the distance between them.
Now suppose that we have a metal ball with two
electrons in it. Where do the electrons go??
19
They should end up somewhere on the outer
perimeterthis will maximize the distance between
them.
Now suppose that we add a third electronwhere
will the three of them end up?
They will end up equidistant from each other, but
at the same time maximizing the distance from one
another.
20
What if there are FOUR charges?
Again, the charges will configure themselves to
maximize the distance from each of the other
charges. The results in them being an
equidistance apart.
21
What if there are 1 x 1015 free electrons in a
conductorwhere do they end up?
They end up spread out evenly on the SURFACE of
the conducting material!!
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