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Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium. [68] About 0.9% of the Sun's mass is oxygen. [19] Oxygen constitutes 49.2% of the Earth's crust by mass [69] as part of oxide compounds such as silicon dioxide and is the most abundant element by mass in the Earth's crust.
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 ...
Joseph Priestley FRS (/ ˈ p r iː s t l i /; [3] 24 March 1733 – 6 February 1804) was an English chemist, Unitarian, natural philosopher, separatist theologian, grammarian, multi-subject educator and classical liberal political theorist. [4]
Photosynthetic prokaryotic organisms that produced O 2 as a byproduct lived long before the first build-up of free oxygen in the atmosphere, [5] perhaps as early as 3.5 billion years ago. The oxygen cyanobacteria produced would have been rapidly removed from the oceans by weathering of reducing minerals, [citation needed] most notably ferrous ...
Liquid oxygen has a clear cyan color and is strongly paramagnetic: it can be suspended between the poles of a powerful horseshoe magnet. [2] Liquid oxygen has a density of 1.141 kg/L (1.141 g/ml), slightly denser than liquid water, and is cryogenic with a freezing point of 54.36 K (−218.79 °C; −361.82 °F) and a boiling point of 90.19 K (−182.96 °C; −297.33 °F) at 1 bar (14.5 psi).
William Robert Grove c. 1850. In 1846, Grove published On The Correlation of Physical Forces [15] [16] in which he anticipated the general theory of the conservation of energy that was more famously put forward in Hermann von Helmholtz' Über die Erhaltung der Kraft (On the Conservation of Force) published the following year. [7]
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In a note at the end of his work "A Dynamical Theory of the Electromagnetic Field", Maxwell discussed a model for gravity based on a medium similar to the one he used for the electromagnetic field. He concluded that the medium would have "an enormous intrinsic energy" and would necessarily have to be diminished in areas of mass.