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  2. Chemical polarity - Wikipedia

    en.wikipedia.org/wiki/Chemical_polarity

    These effects add as vectors to make the overall molecule polar. A polar molecule has a net dipole as a result of the opposing charges (i.e. having partial positive and partial negative charges) from polar bonds arranged asymmetrically. Water (H 2 O) is an example of a polar molecule since it has a slight positive charge on one side and a ...

  3. Hypothetical types of biochemistry - Wikipedia

    en.wikipedia.org/wiki/Hypothetical_types_of...

    False-color Cassini radar mosaic of Titan's north polar region; the blue areas are lakes of liquid hydrocarbons. "The existence of lakes of liquid hydrocarbons on Titan opens up the possibility for solvents and energy sources that are alternatives to those in our biosphere and that might support novel life forms altogether different from those on Earth."—NASA Astrobiology Roadmap 2008 [1]

  4. Biological roles of the elements - Wikipedia

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

    A large fraction of the chemical elements that occur naturally on the Earth's surface are essential to the structure and metabolism of living things. Four of these elements (hydrogen, carbon, nitrogen, and oxygen) are essential to every living thing and collectively make up 99% of the mass of protoplasm. [1]

  5. Timeline of the evolutionary history of life - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_the...

    [15] [16] The Moon's gravitational pull stabilised Earth's fluctuating axis of rotation, setting up regular climatic conditions favoring abiogenesis. [17] 4404 Ma Evidence of the first liquid water on Earth which were found in the oldest known zircon crystals. [18] 4280–3770 Ma Earliest possible appearance of life on Earth. [19] [20] [21] [22]

  6. Water - Wikipedia

    en.wikipedia.org/wiki/Water

    Water is an inorganic compound with the chemical formula H 2 O.It is a transparent, tasteless, odorless, [c] and nearly colorless chemical substance.It is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent [20]).

  7. Formaldehyde - Wikipedia

    en.wikipedia.org/wiki/Formaldehyde

    Formaldehyde appears to be a useful probe in astrochemistry due to prominence of the 1 10 ←1 11 and 2 11 ←2 12 K-doublet transitions. It was the first polyatomic organic molecule detected in the interstellar medium. [29] Since its initial detection in 1969, it has been observed in many regions of the galaxy.

  8. Properties of water - Wikipedia

    en.wikipedia.org/wiki/Properties_of_water

    Water is the most abundant substance on Earth's surface and also the third most abundant molecule in the universe, after H 2 and CO. [23] 0.23 ppm of the earth's mass is water and 97.39% of the global water volume of 1.38 × 10 9 km 3 is found in the oceans. [84]

  9. Molecular geometry - Wikipedia

    en.wikipedia.org/wiki/Molecular_geometry

    It includes the general shape of the molecule as well as bond lengths, bond angles, torsional angles and any other geometrical parameters that determine the position of each atom. Molecular geometry influences several properties of a substance including its reactivity , polarity , phase of matter , color , magnetism and biological activity .