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  2. Acetal - Wikipedia

    en.wikipedia.org/wiki/Acetal

    In contrast to variations of R, both R' groups are organic fragments. If one R' is a hydrogen, the functional group is instead a hemiacetal, while if both are H, the functional group is a ketone hydrate or aldehyde hydrate. Formation of an acetal occurs when the hydroxyl group of a hemiacetal becomes protonated and is lost as water.

  3. 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.

  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. Group (periodic table) - Wikipedia

    en.wikipedia.org/wiki/Group_(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.

  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. List of chemical elements - Wikipedia

    en.wikipedia.org/wiki/List_of_chemical_elements

    A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...

  8. Period (periodic table) - Wikipedia

    en.wikipedia.org/wiki/Period_(periodic_table)

    All period three elements occur in nature and have at least one stable isotope. All but the noble gas argon are essential to basic geology and biology. Sodium (Na) is an alkali metal. It is present in Earth's oceans in large quantities in the form of sodium chloride (table salt). Magnesium (Mg) is an alkaline earth metal.

  9. Category:Acetals - Wikipedia

    en.wikipedia.org/wiki/Category:Acetals

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