Prelim 1
(Wks 16)
Significant Figures
–
Counting:
1.
All nonzero digits are significant.
2.
Zeroes to the left of the first nonzero digit are not significant.
3.
Zeroes at the end of a number that includes a decimal point are
significant.
Addition and Subtraction:

the answer can contain no more decimal places
than the least accurate
measurement
Multiplication and Division:

the answer can contain no more significant figures
than the least accurate
measurement
Scientific Notation
Addition and Subtraction
–
numbers converted to same power of 10,
coefficients added or subtracted and exponent remains
Multiplication
–
coefficients multiplied and exponents added
Division
–
coefficients divided, exponent of divisor is subtracted from
exponent of number being divided
J.J. Thomson
–
cathode ray tubes
–
discovery of electrons
Bohr’s View
–
there are 2n^2 electrons allowed in a level
Modern View
–
orbitals that differ in shape and energy
Filling of Orbitals:
1s
→2s→2p→3s→3p→4s→3d→4p→5s→
4d→5p→6s→4f
(s=2, p=6, d=10, f=14)
Trends
Size of atoms decreases as you move from left to right
Size of atoms increases as you move down a group
Reactivity for metals increases as you move down a group
Reactivity for nonmetals decreases as you move down a column
Groups:
1A
–
Alkali, 2A
–
Alkali Earths
–
harder, more dense, 7A
–
Halogens
–
diatoms, 8A
–
Noble Gases
–
colorless, not reactive
Electromagnetic Radiation:
Λv = C
,
E=hv

Λ
= wavelength, v = frequency, C = speed of light

As Λ decreases, v increases, E increases

As Λ increases, v decreases, E decreases
Troposphere
–
Tropopause (10 km)
–
Stratosphere (Ozone)
–
Mesosphere
(temp decreases as you go higher in the troposphere, and then increases as you
proceed through the stratosphere)

Anthropogenic pollution
–
attributable to human activity

Clean Air Act (1990)
–
regulates particulates, ozone, CO, nitrogen and
sulfur oxides, ozonedepleting chemicals (freons)

Acid Rain
–
H
2
SO
4
(sulfuric acid) acidifies soil and ground water

Thermal Inversion
–polluted cool air can’t
rise above warm air
Photochemical Smog
–
formed by action of sunlight on photoreactive
pollutants in the air
Photodissociation
of nitrogen dioxide:
NO
2
→ NO + O, O
2
+ O → O
3
(NO and NO2 are both pollutants)
RO
2
, NO
2
and aldehydes are in smog

Incomplete combustion
–
insufficient oxygen
–
creates CO
Solutions to Smog and Ozone
Scrub sulfur dioxide from coal emissions, cars with better mileage, electric or
hydrogen, fuel cells, catalytic converters (NO
X
to N
2
), minimize volatile
organic compounds

Rainout
–
pollutants in air removed by natural precipitation
Because a double bond is stronger than a 1.5 bond and requires more energy
to break, oxygen molecules absorb higherenergy UV radiation (UVC)
–
ozone absorbs lower energy (UVB)
–
therefore, ozone is more reactive
toward UV light than is oxygen.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '07
 ARMSTRONG
 Hard Water Ions, water Thermal Inversion, significant water vapor

Click to edit the document details