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  2. Transition metal - Wikipedia

    en.wikipedia.org/wiki/Transition_metal

    The period 6 and 7 transition metals also add core (n − 2)f 14 electrons, which are omitted from the tables below. The p orbitals are almost never filled in free atoms (the one exception being lawrencium due to relativistic effects that become important at such high Z), but they can contribute to the chemical bonding in transition metal ...

  3. Electron transfer - Wikipedia

    en.wikipedia.org/wiki/Electron_transfer

    Electron transfer (ET) occurs when an electron relocates from an atom, ion, or molecule, to another such chemical entity. ET describes the mechanism by which electrons are transferred in redox reactions. [2] Electrochemical processes are ET reactions. ET reactions are relevant to photosynthesis and respiration and commonly involve transition ...

  4. Group 4 element - Wikipedia

    en.wikipedia.org/wiki/Group_4_element

    As is typical for early transition metals, zirconium and hafnium have only the group oxidation state of +4 as a major one, and are quite electropositive and have a less rich coordination chemistry. Due to the effects of the lanthanide contraction, they are very similar in properties. Titanium is somewhat distinct due to its smaller size: it has ...

  5. Periodic table - Wikipedia

    en.wikipedia.org/wiki/Periodic_table

    [39] [58] From gallium onwards, the 3d orbitals form part of the electronic core, and no longer participate in chemistry. [57] The s- and p-block elements, which fill their outer shells, are called main-group elements; the d-block elements (coloured blue below), which fill an inner shell, are called transition elements (or transition metals ...

  6. Main-group element - Wikipedia

    en.wikipedia.org/wiki/Main-group_element

    Main-group elements (with some of the lighter transition metals) are the most abundant elements on Earth, in the Solar System, and in the universe. Group 12 elements are often considered to be transition metals; however, zinc (Zn), cadmium (Cd), and mercury (Hg) share some properties of both groups, and some scientists believe they should be ...

  7. Actinide concept - Wikipedia

    en.wikipedia.org/wiki/Actinide_concept

    In nuclear chemistry, the actinide concept (also known as actinide hypothesis) proposed that the actinides form a second inner transition series homologous to the lanthanides. Its origins stem from observation of lanthanide-like properties in transuranic elements in contrast to the distinct complex chemistry of previously known actinides.

  8. Iron - Wikipedia

    en.wikipedia.org/wiki/Iron

    Iron shows the characteristic chemical properties of the transition metals, namely the ability to form variable oxidation states differing by steps of one and a very large coordination and organometallic chemistry: indeed, it was the discovery of an iron compound, ferrocene, that revolutionalized the latter field in the 1950s. [59]

  9. 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]