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  2. Metal ions in aqueous solution - Wikipedia

    en.wikipedia.org/wiki/Metal_ions_in_aqueous_solution

    A metal ion in aqueous solution or aqua ion is a cation, dissolved in water, of chemical formula [M(H 2 O) n] z+.The solvation number, n, determined by a variety of experimental methods is 4 for Li + and Be 2+ and 6 for most elements in periods 3 and 4 of the periodic table.

  3. Iron in biology - Wikipedia

    en.wikipedia.org/wiki/Iron_in_biology

    Iron can also be oxidized by marine microbes under conditions that are high in iron and low in oxygen. [53] Iron can enter marine systems through adjoining rivers and directly from the atmosphere. Once iron enters the ocean, it can be distributed throughout the water column through ocean mixing and through recycling on the cellular level. [54]

  4. Properties of water - Wikipedia

    en.wikipedia.org/wiki/Properties_of_water

    Water molecules stay close to each other , due to the collective action of hydrogen bonds between water molecules. These hydrogen bonds are constantly breaking, with new bonds being formed with different water molecules; but at any given time in a sample of liquid water, a large portion of the molecules are held together by such bonds. [61]

  5. Abundance of the chemical elements - Wikipedia

    en.wikipedia.org/wiki/Abundance_of_the_chemical...

    Another scale is mass fraction or, equivalently, percent by mass. [2] For example, the abundance of oxygen in pure water can be measured in two ways: the mass fraction is about 89%, because that is the fraction of water's mass which is oxygen. However, the mole fraction is about 33% because only 1 atom of 3 in water, H 2 O, is oxygen.

  6. Composition of the human body - Wikipedia

    en.wikipedia.org/wiki/Composition_of_the_human_body

    Water is ~11% hydrogen by mass but ~67% hydrogen by atomic percent, and these numbers along with the complementary % numbers for oxygen in water, are the largest contributors to overall mass and atomic composition figures. Because of water content, the human body contains more oxygen by mass than any other element, but more hydrogen by atom ...

  7. Biological roles of the elements - Wikipedia

    en.wikipedia.org/wiki/Biological_roles_of_the...

    oxygen: 8: 5: Ubiquitous, essential for all forms of life; essentially all biological molecules (not to mention water) contain substantial amounts of oxygen. [11] In high concentrations, oxygen toxicity can occur. palladium: 46: 2a: Has no known biological role. [11]

  8. Water splitting - Wikipedia

    en.wikipedia.org/wiki/Water_splitting

    In thermolysis, water molecules split into hydrogen and oxygen. For example, at 2,200 °C (2,470 K; 3,990 °F) about three percent of all H 2 O are dissociated into various combinations of hydrogen and oxygen atoms, mostly H, H 2, O, O 2, and OH. Other reaction products like H 2 O 2 or HO 2 remain minor. At the very high temperature of 3,000 ...

  9. Iron compounds - Wikipedia

    en.wikipedia.org/wiki/Iron_compounds

    The dihydrate of iron(II) oxalate has a polymeric structure with co-planar oxalate ions bridging between iron centres with the water of crystallisation located forming the caps of each octahedron, as illustrated below. [22] Crystal structure of iron(II) oxalate dihydrate, showing iron (gray), oxygen (red), carbon (black), and hydrogen (white ...