Second Lecture a Janusry 27 2011

8/3/2019 Second Lecture a Janusry 27 2011

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16 weeks two lectures per week

one lab per week as listed in syllabus

Test every third week at the end of the Friday class.

There will be a total of5 tests.

The lowest score will be dropped unless a test is

missed.


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First week: chapters 1-3

Second week: chapter 4Third week: chapter 5

Pay attention to the Learning Outcomes

highlighted in each chapter.

Test questions will be multiple choice or short answer

questions modeled on the questions at the end of

each chapter.


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DOMAINS


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Question

Hypothesis

PredictionsExperiments

Conclusion

Scientific Method

Proven hypotheses lead to theories.


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1858 Hypothesis:

Natural selection is the mechanism for evolution.

Individuals possessing attributes that give them an

advantage in their environment are more likely to

survive and reproduce.

Therefore the population gradually changes.

Decent with modification = evolution


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Bhor


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Oxygen oxidizes things, oxygen always gains electrons

Oxidized molecule looses electrons.

Oxidation is the loss of electrons.Reduction is the gain of electrons.

In an oxidation reaction, oxygen itself is reduced.


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Each period: same # valence electrons in in outermost shell


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Atomic mass is the sum of the mass ofelectrons, protons and neutrons .

Isotopes have same number of protonsand electrons but differ in the number

neutrons.


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Covalent bonds

Molecules contain 2 or more atomsjoined by covalent bonds.

The resulting molecule has no netcharge.

The octet rule is satisfied, therefore

there are no unpaired electrons.


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Structural

formulaMolecular

formula


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Covalent bonds can be polar or non polar

depending on the individual atoms

affinity for electrons (electronegativity)


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The water molecule is polar.


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Hydrogen bond is a fixed length

causing ice to be less dense than liqiud.


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Properties

ofWater

mostly

liquidat earth

surface

Can adhere to

other polarmolecules

(capillary action)


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One ml (cc) ofwater

at 250C and 1 atmosphereweighs 1 gram (g)

One gram ofhydrogencontains 6.02 X 1023 molecules

6.02 X 1023 molecules = 1 mole


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Molecular weight = weight of one mole

One mole of hydrogen weighs 1 g

One mole of oxygen weighs 16 g

Molecular weight of water is

2 X 1 g + 1 X 16 g = 18 g

The molecular weight of water is 18 g


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1 liter = 1000ml = 1000g

Molecular weight of water is

18 g/mole

One liter of water contains

1000/18

55 moles of water


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Water undergoes ionization:

H2O OH-

+ H+

At 250C one liter of water contains 10-7

mole of H+ ions.


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Acids and Basis

pH is a measure of the concentration ofhydrogen ions in solution.

pH is measure of the [H+

] in solution.

pH = -log [H+]

pH scale is 0 to 14 (acidic to basic)


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pH = -log [H+]

0.1 mole H+/liter has a pH = 1

(-log 10-1 = 1)

10-14 mole H+/liter has pH = 14

(-log 10-14 =14)

pH scale is 0 to 14 (acidic to basic)


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Buffers stabilize pH.

At their buffering range they bind excess[H+] as pH decreases and supply [H+] as

pH increases.

Dissolved carbon dioxide (carbonic

acid/bicarbonate)is the key buffer in

human blood. Its buffering range is from

pH 4 to 6.


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Eratosthenes (Er-uh-tos-thuh-neez)

Second Lecture a Janusry 27 2011

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