Tuesday, November 27, 2007
Tues-Day 2
Bio - we introduced the life process of photosynthesis in which light energy is used to convert inorganic carbon dioxide and water into glucose and oxygen. The radiant/light energy from the sun is ultimately stored in the covalent bonds in glucose as chemical potential energy; the oxygen gas is a by-product due to the "splitting" of the water molecules via photolysis that occurs during photosynthesis.
We discussed the organelle in which photosynthesis occurs: the choroplast. Key structures of the chloroplast are the grana, which are stacks of thylakoid "pankcake-shaped" structures that contain the light/energy absorbing pigment, chlorophyll. The other key region of the chloroplast is the STROMA, which is the jelly-like material that surrounds the grana, where glucose is synthesized.
We also saw that green plants have more than one type of chlorophyll pigment in their chloroplasts as well as other light-absorbing pigments e.g. carotenes and xanthophylls. These various pigments are advantageous to plants because more and different colors of light energy can then be absorbed by the plant so that it can have the energy for photosynthesis.
Finally, we saw that chlorophyll a and chorophyll b best absorb red light and blue light but that they REFLECT/do not absorb green light, which is why plants appear green. Thus, photosynthetic rate will be greatest when blue and/or red light is used.
Chem 7/8- we discussed the Bohr Model of the Atom, which shows each electron in an orbit that corresponds to the specific energy of the electron. The farther away the orbit of the electron from the nucleus, the higher the electron's energy.
Bohr's Model explains how atoms of a given element, when excited by an energy source, will emit only specific energy photons. Here's the important thing: the specific energy of each emitted photon is EXACTLY equal to the energy lost by the electron as the electron went from a higher principal energy level to a lower principal energy level; furthermore, the energy of the emitted photon is EXACTLY equal to the DIFFERENCE in energy between these two energy levels.
Each element has a different number of protons causing the electrons in its atoms to have a different and unique potential energy levels. So, NO TWO elements have the same difference in energy between ANY two corresponding energy levels. Thus, an electron that goes from n=5 to n=2 in a Hydrogen atom will emit a DIFFERENT energy photon than an electron that goes from n=5 to n=2 in an atom of ANY OTHER element. On Blackboard, I have posted the light emission spectrum video that explains the electron energy transitions in an atom.
We then finished our weighted average atomic mass lab, with emphasis on the atomic mass definition and calculations. We also did typical lab data calculations in which we practiced sig figs
and percent error.
Chem 9- we discussed the Bohr Model of the Atom, which shows each electron in an orbit that corresponds to the specific energy of the electron. The farther away the orbit of the electron from the nucleus, the higher the electron's energy.
Bohr's Model explains how atoms of a given element, when excited by an energy source, will emit only specific energy photons. Here's the important thing: the specific energy of each emitted photon is EXACTLY equal to the energy lost by the electron as the electron went from a higher principal energy level to a lower principal energy level; furthermore, the energy of the emitted photon is EXACTLY equal to the DIFFERENCE in energy between these two energy levels.
Each element has a different number of protons causing the electrons in its atoms to have a different and unique potential energy levels. So, NO TWO elements have the same difference in energy between ANY two corresponding energy levels. Thus, an electron that goes from n=5 to n=2 in a Hydrogen atom will emit a DIFFERENT energy photon than an electron that goes from n=5 to n=2 in an atom of ANY OTHER element. On Blackboard, I have posted the light emission spectrum video that explains the electron energy transitions in an atom.
We discussed the organelle in which photosynthesis occurs: the choroplast. Key structures of the chloroplast are the grana, which are stacks of thylakoid "pankcake-shaped" structures that contain the light/energy absorbing pigment, chlorophyll. The other key region of the chloroplast is the STROMA, which is the jelly-like material that surrounds the grana, where glucose is synthesized.
We also saw that green plants have more than one type of chlorophyll pigment in their chloroplasts as well as other light-absorbing pigments e.g. carotenes and xanthophylls. These various pigments are advantageous to plants because more and different colors of light energy can then be absorbed by the plant so that it can have the energy for photosynthesis.
Finally, we saw that chlorophyll a and chorophyll b best absorb red light and blue light but that they REFLECT/do not absorb green light, which is why plants appear green. Thus, photosynthetic rate will be greatest when blue and/or red light is used.
Chem 7/8- we discussed the Bohr Model of the Atom, which shows each electron in an orbit that corresponds to the specific energy of the electron. The farther away the orbit of the electron from the nucleus, the higher the electron's energy.
Bohr's Model explains how atoms of a given element, when excited by an energy source, will emit only specific energy photons. Here's the important thing: the specific energy of each emitted photon is EXACTLY equal to the energy lost by the electron as the electron went from a higher principal energy level to a lower principal energy level; furthermore, the energy of the emitted photon is EXACTLY equal to the DIFFERENCE in energy between these two energy levels.
Each element has a different number of protons causing the electrons in its atoms to have a different and unique potential energy levels. So, NO TWO elements have the same difference in energy between ANY two corresponding energy levels. Thus, an electron that goes from n=5 to n=2 in a Hydrogen atom will emit a DIFFERENT energy photon than an electron that goes from n=5 to n=2 in an atom of ANY OTHER element. On Blackboard, I have posted the light emission spectrum video that explains the electron energy transitions in an atom.
We then finished our weighted average atomic mass lab, with emphasis on the atomic mass definition and calculations. We also did typical lab data calculations in which we practiced sig figs
and percent error.
Chem 9- we discussed the Bohr Model of the Atom, which shows each electron in an orbit that corresponds to the specific energy of the electron. The farther away the orbit of the electron from the nucleus, the higher the electron's energy.
Bohr's Model explains how atoms of a given element, when excited by an energy source, will emit only specific energy photons. Here's the important thing: the specific energy of each emitted photon is EXACTLY equal to the energy lost by the electron as the electron went from a higher principal energy level to a lower principal energy level; furthermore, the energy of the emitted photon is EXACTLY equal to the DIFFERENCE in energy between these two energy levels.
Each element has a different number of protons causing the electrons in its atoms to have a different and unique potential energy levels. So, NO TWO elements have the same difference in energy between ANY two corresponding energy levels. Thus, an electron that goes from n=5 to n=2 in a Hydrogen atom will emit a DIFFERENT energy photon than an electron that goes from n=5 to n=2 in an atom of ANY OTHER element. On Blackboard, I have posted the light emission spectrum video that explains the electron energy transitions in an atom.
# posted by C @ 11:41 AM 
