Karlene Joseph (Lane Tech HS) -- Gas Laws
Karlene first showed a diagram that allows us to determine how electrons fill atomic orbitals, from lower energy to higher energy:
|Sub-shells (# electrons)||Atomic Number|
for Full Sub-shell
|2||2s2 2p6||4 10|
|3||3s2 3p6 3d10||12 18 30|
|4||4s2 4p6 4d10 4f14||20 36 48 68|
|5||5s2 5p6 5d10 5f14||38 54 78 102|
|6||6s2 6p6 6d10||12 84 112|
|7||3s2 7p6||86 118|
The filled P-subshells occur for noble gases: Z= 2 (Helium), 10 (Neon), 18 (Argon), 36 (Krypton), 54 (Xenon), 84 (Radon), and 118 (żż Valium ??). It appears as though atoms with atomic number of 118 are at about the limit of discovery.
Karlene next considered the role of oxygen in cellular respiration. She began by posing these three questions:
|How long can humans live without food? ..........||Perhaps 2-3 weeks|
|How long can humans live without water?||Perhaps 2-3 days|
|How long can humans live without oxygen?||Perhaps 5 minutes|
Now we come to the topic of electron transport. The compounds NADH and FADH2 donate high energy electrons to a transport chain in the inner mitochondrial membrane. As the electrons are passed from one component of the chain to the next, and ultimately to hydrogen ions H+ and O2 molecules to form water, energy is released and used to pump hydrogen ions H+ from the mitochondrial matrix into the inter-membrane space. The hydrogen ion then moves back from the region of high concentration [inter-membrane space] to low concentration [matrix] and releases energy. The energy released in this process is used to form ATP from ADP, thereby storing more energy in the cell. It is estimated that as many as 34 ATP molecules can be created from the energy in a single glucose molecule by this process of electron transport. Consequently, one can store the energy in a single glucose molecule by creating up to 38 ATP molecules.
Karlene then had us form a (human) electron transport chain, with each person being either part of the electron transport chain (passing electrons on to the next link) or to a second cycle of (human} "oxygens" taking up electrons at the end of the chain and producing water at the same rate as electrons are passing through the chain. We then reduced the number of "oxygens" by about 60%, so that the electron chain is forced to move more slowly. If all the "oxygens" sat down, no electron transport could occur, and we would lose the energy stored in 34 ATP's.
Great activity, and great lesson, Karlene!
Notes taken by Ben Stark