Transcript Thursday, January 22

Chemistry 102
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Dr. Don DeCoste
367J Noyes Lab
[email protected]
3-4 pm Tuesdays and Thursdays
By appointment; open door policy
http://chem.illinois.edu
1
To Do
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Read Chapters 1 and 2.
Text homework for Chapters 1
and 2.
Lon-Capa assignment #1.
2
Uncertainty in Measurement
3
Clicker Question
How many significant
figures should be
reported?
a)
b)
c)
d)
e)
1
2
3
4
5
4
Clicker Question
What is the volume
reading of the buret?
a)
b)
c)
d)
e)
20.14
20.15
20.16
20.17
20.18
5
Clicker Question
How many significant figures are in the
measurement 0.030140 liters?
a)
b)
c)
d)
e)
3
4
5
6
7
6
Clicker Question
You add 82.4 mL of water in a graduated
cylinder to 25 mL of water in a beaker.
How much water should you report?
a)
b)
c)
d)
e)
100 mL (1 significant figure)
110 mL (2 significant figures)
110. mL (3 significant figures)
107 mL (3 significant figures)
107.4 (4 significant figures)
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Clicker Question
In the last problem you added 82.4 mL
and 25 mL to get an answer reported to
3 significant figures. What is the final
reported answer if you multiply 82.4 cm
and 25 cm?
a)
b)
c)
d)
e)
2000 cm2 (1 significant figure)
2100 cm2 (2 significant figures)
2060 cm2 (3 significant figures)
2.10 x 103 cm2 (3 significant figures)
2060. cm2 (4 significant figures)
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Particulate Nature of Matter
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Atom: smallest part of an element
that is still that element
(fundamental unit of which
elements are composed).
Molecule: Two or more atoms
joined and acting as a unit.
(element or compound)
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Atomic Element
10
Molecular Elements
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Compounds
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Macroscopic versus Microscopic
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Chemistry – A Big Idea
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Atoms have structure.
Subatomic particles – electrons,
protons, and neutrons.
 Atoms are mostly open space.
 Atoms can attract (and repel) one
another.
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Atomic Structure–So What?
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Bonds form within molecules.
Molecules are sticky (forces between
molecules).
Different reactivities of elements (why
is He in Mylar balloons?).
Fireworks.
Pools close during a thunderstorm.
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