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Photosynthetic oxygen evolution is the fundamental process by which oxygen is generated in the earth's biosphere. The reaction is part of the light-dependent reactions of photosynthesis in cyanobacteria and the chloroplasts of green algae and plants. It utilizes the energy of light to split a water molecule into its protons and electrons for ...
Discovered that electric attraction and repulsion can act across a vacuum and does not depend upon the air as a medium. He also added resin to the then-known list of "electrics". 1678: Christiaan Huygens: Stated his theory to the French Academy of Sciences that light is a wave-like phenomenon. 1687: Sir Isaac Newton
The common allotrope of elemental oxygen on Earth is called dioxygen, O 2, the major part of the Earth's atmospheric oxygen (see Occurrence). O 2 has a bond length of 121 pm and a bond energy of 498 kJ/mol. [42] O 2 is used by complex forms of life, such as animals, in cellular respiration. Other aspects of O 2 are covered in the remainder of ...
Significant concentrations of oxygen were just one of the prerequisites for the evolution of complex life. [9] Models based on uniformitarian principles (i.e. extrapolating present-day ocean dynamics into deep time) suggest that such a concentration was only reached immediately before metazoa first appeared in the fossil record. [9]
A molecular vibration is a periodic motion of the atoms of a molecule relative to each other, such that the center of mass of the molecule remains unchanged. The typical vibrational frequencies range from less than 10 13 Hz to approximately 10 14 Hz, corresponding to wavenumbers of approximately 300 to 3000 cm −1 and wavelengths of approximately 30 to 3 μm.
A photooxygenation is a light-induced oxidation reaction in which molecular oxygen is incorporated into the product(s). [1] [2] Initial research interest in photooxygenation reactions arose from Oscar Raab's observations in 1900 that the combination of light, oxygen and photosensitizers is highly toxic to cells. [3]
Using analogies based on the experiences of the senses, he gave a picture or an image of an atom in which atoms were distinguished from each other by their shape, their size, and the arrangement of their parts. Moreover, connections were explained by material links in which single atoms were supplied with attachments: some with hooks and eyes ...
Solid oxygen O 2, like liquid oxygen, is a clear substance with a light sky-blue color caused by absorption in the red part of the visible light spectrum. Oxygen molecules have attracted attention because of the relationship between the molecular magnetization and crystal structures, electronic structures, and superconductivity.