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  2. DNA - Wikipedia

    en.wikipedia.org/wiki/DNA

    The two DNA strands are known as polynucleotides as they are composed of simpler monomeric units called nucleotides. [2] [3] Each nucleotide is composed of one of four nitrogen-containing nucleobases (cytosine [C], guanine [G], adenine [A] or thymine [T]), a sugar called deoxyribose, and a phosphate group.

  3. Lewis structure - Wikipedia

    en.wikipedia.org/wiki/Lewis_structure

    Initially, one line (representing a single bond) is drawn between each pair of connected atoms. Each bond consists of a pair of electrons, so if t is the total number of electrons to be placed and n is the number of single bonds just drawn, t−2n electrons remain to be placed. These are temporarily drawn as dots, one per electron, to a maximum ...

  4. Nucleic acid structure - Wikipedia

    en.wikipedia.org/wiki/Nucleic_acid_structure

    A nucleic acid sequence is the order of nucleotides within a DNA (GACT) or RNA (GACU) molecule that is determined by a series of letters. Sequences are presented from the 5' to 3' end and determine the covalent structure of the entire molecule. Sequences can be complementary to another sequence in that the base on each position is complementary ...

  5. Molecular orbital diagram - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital_diagram

    For a diatomic molecule, an MO diagram effectively shows the energetics of the bond between the two atoms, whose AO unbonded energies are shown on the sides. For simple polyatomic molecules with a "central atom" such as methane (CH 4) or carbon dioxide (CO 2), a MO diagram may show one of the identical bonds to the central atom. For other ...

  6. Orbital hybridisation - Wikipedia

    en.wikipedia.org/wiki/Orbital_hybridisation

    Chemist Linus Pauling first developed the hybridisation theory in 1931 to explain the structure of simple molecules such as methane (CH 4) using atomic orbitals. [2] Pauling pointed out that a carbon atom forms four bonds by using one s and three p orbitals, so that "it might be inferred" that a carbon atom would form three bonds at right angles (using p orbitals) and a fourth weaker bond ...

  7. Chemical structure - Wikipedia

    en.wikipedia.org/wiki/Chemical_structure

    A chemical structure of a molecule is a spatial arrangement of its atoms and their chemical bonds. Its determination includes a chemist 's specifying the molecular geometry and, when feasible and necessary, the electronic structure of the target molecule or other solid. Molecular geometry refers to the spatial arrangement of atoms in a molecule ...

  8. Chemical bond - Wikipedia

    en.wikipedia.org/wiki/Chemical_bond

    A single bond between two atoms corresponds to the sharing of one pair of electrons. The Hydrogen (H) atom has one valence electron. Two Hydrogen atoms can then form a molecule, held together by the shared pair of electrons. Each H atom now has the noble gas electron configuration of helium (He).

  9. Lone pair - Wikipedia

    en.wikipedia.org/wiki/Lone_pair

    Lone pair. In science, a lone pair refers to a pair of valence electrons that are not shared with another atom in a covalent bond [1] and is sometimes called an unshared pair or non-bonding pair. Lone pairs are found in the outermost electron shell of atoms. They can be identified by using a Lewis structure.