enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Acetal - Wikipedia

    en.wikipedia.org/wiki/Acetal

    Generic structure of acetals. In organic chemistry, an acetal is a functional group with the connectivity R 2 C(OR') 2.Here, the R groups can be organic fragments (a carbon atom, with arbitrary other atoms attached to that) or hydrogen, while the R' groups must be organic fragments not hydrogen.

  3. CHNOPS - Wikipedia

    en.wikipedia.org/wiki/CHNOPS

    Graphic representation of carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. CHNOPS and CHON are mnemonic acronyms for the most common elements in living organisms. . "CHON" stands for carbon, hydrogen, oxygen, and nitrogen, which together make up more than 95 percent of the mass of biological system

  4. Acetyl group - Wikipedia

    en.wikipedia.org/wiki/Acetyl_group

    In IUPAC nomenclature, an acetyl group is called an ethanoyl group. An acetyl group contains a methyl group ( −CH 3 ) that is single-bonded to a carbonyl ( C=O ), making it an acyl group . The carbonyl center of an acyl radical has one non-bonded electron with which it forms a chemical bond to the remainder (denoted with the letter R ) of the ...

  5. Functional group - Wikipedia

    en.wikipedia.org/wiki/Functional_group

    The reactivity of a functional group can be modified by other functional groups nearby. Functional group interconversion can be used in retrosynthetic analysis to plan organic synthesis. A functional group is a group of atoms in a molecule with distinctive chemical properties, regardless of the other atoms in the molecule.

  6. Composition of the human body - Wikipedia

    en.wikipedia.org/wiki/Composition_of_the_human_body

    Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...

  7. Periodic table - Wikipedia

    en.wikipedia.org/wiki/Periodic_table

    a Group 1 is composed of hydrogen (H) and the alkali metals. Elements of the group have one s-electron in the outer electron shell. Hydrogen is not considered to be an alkali metal as it is not a metal, though it is more analogous to them than any other group. This makes the group somewhat exceptional.

  8. 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]

  9. Carbon-based life - Wikipedia

    en.wikipedia.org/wiki/Carbon-based_life

    Carbon is the 15th most abundant element in the Earth's crust, and the fourth most abundant element in the universe by mass, after hydrogen, helium, and oxygen. Carbon's widespread abundance, its ability to form stable bonds with numerous other elements, and its unusual ability to form polymers at the temperatures commonly encountered on Earth ...