Flashcards in Chapter 2 - Protecting the Ozone Layer Deck (50):
What is the formula for ozone?
energy + 3 O2 --> 2 O3
What is ozone?
an allotropic form of energy (different form of same element, differ in structure and properties)
What are the characteristics of oxygen?
-light blue liquid
-boiling point: -193 degrees (gas --> liquid)
-reactive (supports combustion)
What are the characteristics of ozone?
-dark blue liquid
-boiling point: -112 degrees (gas --> liquid)
Where is ozone found?
-majority in stratosphere
-also found in troposphere (ozone increases from pollution)
Good vs. Bad Ozone
Good: in upper atmosphere ozone blocks UV rays
-90% of ozone is in "ozone layer" (9.3-18.6 miles above ground)
Bad: lower atmosphere ozone produces photochemical smog
-10% of ozone here at 1.5 miles above ground and lower
What is the structure of an atom?
nucleus: center, dense, contains protons/neutrons
electrons: orbit nucleus
What are the elementary particles of atoms?
-orbit atom nucleus
-very tiny (compared to protons/neutrons)
-2000x size of electron
-2000x electron size (but heavier than protons)
What are the protons and neutrons called?
What is a neutral atom?
when the # of protons = # of electrons
What determines an element's identity?
depends on # of protons (atomic #, above symbol)
What are ions?
when an element has a different number of electrons
-atomic particle with a charge
-->ex. 17 protons and 18 electrons = +1 charge
17 protons and 16 electrons = -1 charge
What are isotopes?
when an element has a different number of neutrons
-->ex. 6p, 6n, 6e = Carbon-12
6p, 7n, 6e = Carbon-13
6p, 8n, 6e = Carbon-14
What are neutrons?
-add mass to atoms
-change # of neutrons --> same kind of atom physically, reacts the same, same mass, may affect stability (heavier = less stability --> isotopes
atomic mass (not mass #)
What does changing the number of particles do?
-protons --> identity of atom
-neutrons --> isotopes
-electrons --> ions
What are valence electrons?
larger atoms - many electron layers
-valence = outermost electrons
-involved in reactions
-determine chemical properties
-"want" same # of valence electrons as nearest Group 8A element (noble gases-stable/unreactive)
-Group # tells number of valence electrons
What are molecules?
when 2 or more atoms are bound
What is a covalent bond?
when atoms share electrons
-2 electrons shared between 2 atoms = single covalent bond
-4 electrons shared between 2 atoms = double covalent bond
-6 electrons shared between 2 atoms = triple covalent bond
What are Lewis Structures?
Show the electron pairing between atoms
What is the octet rule?
atoms prefer to have 8 valence electrons (shared + unshared)
--> exceptions are H or He (which have 2 electrons max)
Steps to drawing Lewis Structures
1. Find # of valence electrons
2. Write the skeletal structure
3. Put electrons around the "outside" atoms until octet
4. Put any remaining electrons on central atom
5. Assign formula charge
6. If needed, use lone pairs from "outside atoms" to make multiple bonds giving central atoms an octet
--> must satisfy octet over neutral charges
Oxygen vs. Ozone
Why is there a reactivity difference between oxygen and ozone?
oxygen has a double bond, hard to break = less reactive
ozone has a single bond, easier to break = more reactive
What is the relationship between wavelength and frequency?
-longer wavelength (waves per second) = lower frequency
What is the speed of light?
3 x 10^8 m/s
What are the units of frequency?
sec^-1: inverse seconds, cycles per second
-different wavelength = different kind of light
What is the equation for energy?
E = H x v
What is the equation for frequency?
v = c / wavelength
What is the relation between energy, frequency, and wavelength?
increased energy = increased frequency = shorter wavelength
What are the three types of light that come from the sun?
1. visible: most intense
2. IR: most abundant (53%)
3. UV: most damaging (higher freq/energy)
What are the characteristics of light?
-lights is a particle
-light has no mass
-light moves in waves
What is the unit of energy?
What is Planck's constant?
6.63 x 10^-34 Jxs
What happens when light hits matter?
1. IR- molecules vibrate, matter heats up
2. Visible- excites electrons, chemical reactions can occur (photosynthesis)
3. UV- knock electrons off --> charged particles
4. higher frequency UV- break covalent bond (disrupt biological processes, damage tissues, cancer)
least damaging, most abundant on earth
more energy than UV-A
more damaging than UV-A, mostly absorbed by ozone in stratosphere
almost completely absorbed by oxygen and ozone in stratosphere
What is the difference in absorption in oxygen vs. ozone?
Why does ozone absorb a broader range of light?
it is more reactive
"bond and a half" weaker than a double bond in oxygen
What are the biological effects of UV radiation?
-consequences depend on: energy of radiation, sensitivity to light, and time of exposure
-melanoma: linked with intensity and latitude of which you live
What is our cause for concern of UV radiation?
-short wavelengths = massive DNA cleavage
-280nm is 100,000 times more damaging than 320nm
-ozone concentration is dropping
What are natural causes of ozone fluctuation?
-seasonal variation of UV intensity
-sunspot activity cycles
-wind: cloud cover
What causes ozone destruction naturally?
What are Chlorofluorocarbons?
-Cl + F + C
-man made gases
-unreactive (nontoxic, nonflammable, cheap)
What are halons?
-C + Br + Cl or F