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  2. Coordinate covalent bond - Wikipedia

    en.wikipedia.org/wiki/Coordinate_covalent_bond

    In coordination chemistry, a coordinate covalent bond, [1] also known as a dative bond, [2] dipolar bond, [1] or coordinate bond [3] is a kind of two-center, two-electron covalent bond in which the two electrons derive from the same atom. The bonding of metal ions to ligands involves this kind of interaction. [4]

  3. Lewis acids and bases - Wikipedia

    en.wikipedia.org/wiki/Lewis_acids_and_bases

    Lewis had suggested in 1916 that two atoms are held together in a chemical bond by sharing a pair of electrons. [18] When each atom contributed one electron to the bond, it was called a covalent bond. When both electrons come from one of the atoms, it was called a dative covalent bond or coordinate bond. The distinction is not very clear-cut.

  4. Covalent bond classification method - Wikipedia

    en.wikipedia.org/wiki/Covalent_bond...

    However, these ligands also form dative covalent bonds like the L-type. [2] This type of ligand is not usually used because in certain situations it can be written in terms of L and X. For example, if a Z ligand is accompanied by an L type, it can be written as X 2. Examples of these ligands are Lewis acids, such as BR 3. [3]

  5. Resonance (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Resonance_(chemistry)

    Under the framework of valence bond theory, resonance is an extension of the idea that the bonding in a chemical species can be described by a Lewis structure. For many chemical species, a single Lewis structure, consisting of atoms obeying the octet rule, possibly bearing formal charges, and connected by bonds of positive integer order, is sufficient for describing the chemical bonding and ...

  6. Past paper - Wikipedia

    en.wikipedia.org/wiki/Past_paper

    A past paper is an examination paper from a previous year or previous years, usually used either for exam practice or for tests such as University of Oxford, [1] [2] University of Cambridge [3] College Collections.

  7. Dimerization - Wikipedia

    en.wikipedia.org/wiki/Dimerization

    In chemistry, dimerization is the process of joining two identical or similar molecular entities by bonds. The resulting bonds can be either strong or weak. Many symmetrical chemical species are described as dimers, even when the monomer is unknown or highly unstable. [1] The term homodimer is used when the two subunits are identical (e.g.

  8. Ligand field theory - Wikipedia

    en.wikipedia.org/wiki/Ligand_field_theory

    The corresponding anti-bonding orbitals are higher in energy than the anti-bonding orbitals from σ bonding so, after the new π bonding orbitals are filled with electrons from the metal d-orbitals, Δ O has increased and the bond between the ligand and the metal strengthens.

  9. Principles of Biology - Wikipedia

    en.wikipedia.org/wiki/Principles_of_Biology

    The modules combine text, images, simulations, interactive exercises, self-tests, and formal tests. The book draws on the science journal Nature's archive of research papers. It was created by a group of more than 100 scientists, instructors, scientific illustrators, interaction designers, and faculty reviewers. It is available in formats for ...