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1 Chapter 1 — Introduction
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CHAPTER 1!
Matter, Measurement, and Problem Solving!
Chemistry (Custom UMD Edition) #
Nivaldo J. Tro#
Lectures notes by E. Chang!
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Some forefronts of science and the general type of chemical knowledge required: !
Biosensing !Genetic
Engineering ! Nanoscience !Chemical bond formation !
√! √! √!
Molecular Geometry !
√! √! √!
Coordination Chemistry !
√! √! √!
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Is the science that seeks to understand the behavior of matter by studying the
behavior of atoms and molecules: its properties, the changes that substances
undergo, how and why the changes occur, and the energy associated with
these changes.!
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Observation!
Testable! Hypothesis!
Test!Hypothesis!
Modified Theory!
A "Law" is something that is observed to be always true, but has no theoretical foundation.
Improved Instruments!
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• fixed volume!• fixed shape!
fixed volume! • no fixed volume!• no fixed shape!
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Here is one way to diagram matter
Au(s) Fe(s) H2(g)
water H2O(l) rust Fe2O3(s) methane CH4(g)
gasoline alloys air
Ice cream sand concrete
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Energy is conserved, not destroyed.
Potential and kinetic energy can be interconverted.
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• Positive and negative particles (ions)
attract one another.!• Two atoms can bond !
• As the particles attract they have a
lower potential energy!
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The chemical potential energy of a substance
results from the relative positions and
the attractions and repulsions among all
its particles.!
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translate
rotate
vibrate
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Property Unit Abbrev. Mass Kilogram Kg Length meter m Time second s Temperature Kelvin K
Prefix Abbreviation Numerical Equivalent Kilo k 103 Mega M 106 Giga G 109
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• Meter: Distance traveled by light in vacuo in 1/299,792,458 of a second.!
• Second: Duration of 9 192 631 770 periods of microwave radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.!
• Kilogram: A right-cylindrical (90% platinum and 10% iridium) in the basement of the BIPM’s House of Breteuil in Sèvres on the outskirts of Paris.!
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Present and future forms of the kilogram.!
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A Length B Volume C Mass
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Prefix Abbreviation Numerical Equivalent deci d 10-1 centi c 10-2 milli m 10-3 micro 10-6 nano n 10-9 pico p 10-12
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1 in = 2.54 cm ! ! !1 in = 2.54 cm!1 in2 = 6.45 cm2 ! ! !1 in3 = 16.4 cm3!
Note: cm3 does not mean c(m3), but means (cm)3 !
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Anders Celsius 1701-1744
Lord Kelvin (William Thomson) 1824-1907
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oF oC K
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Addition and Subtraction:!
The result of an addition or subtraction should have the same number of decimal places as that number with the least number of decimal places.!
Multiplication and Division:!
The result should have no more significant figures than that number with the least number of significant figures.!
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If < 5 leave next higher s.f. alone
If > 5 round next higher s.f. up
If = 5 Leave alone if even round up if odd
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1. Find units of answer
2. Look at units of what is given
3. Treat units as "numbers" and manipulate them mathematically to get answer units.
Example: How many yards in 100. meters?
1 meter = 1.094 yards
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Things to be aware of:!• Use linear units definitions to find
derived units relationships!• cm2 ≠ c(m)2!• cm2 = (cm)2!
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Density = mass (g)volume (cm3)
Mercury
Aluminum
Platinum
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Density = mass (g)volume (cm3)
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0.95 mm • 1cm 10 mm
= 0.095 cm
57.54 g6.4 cm3 = 9.0 g / cm3
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Element Z Symbol Origin
Sodium 11 Na natrium (L) alkali substance
Potassium 19 K kalium (G), al-quali the ash
Silver 47 Ag argentum (L/sanskrit) shining
Tungstun 74 W wolfram (G) wolf dirt, mineral
Gold 79 Au aurum (sanskrit) yellow
Mercury 80 Hg hydro-argyros (gk) water-silver
Lead 82 Pb plumbum nigram (L) lead (?)
