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[1] [2] [3] Introduced by Gilbert N. Lewis in his 1916 article The Atom and the Molecule, a Lewis structure can be drawn for any covalently bonded molecule, as well as coordination compounds. [4] Lewis structures extend the concept of the electron dot diagram by adding lines between atoms to represent shared pairs in a chemical bond.
Sodium sulfide is a chemical compound with the formula Na 2 S, or more commonly its hydrate Na 2 S·9H 2 O.Both the anhydrous and the hydrated salts in pure crystalline form are colorless solids, although technical grades of sodium sulfide are generally yellow to brick red owing to the presence of polysulfides and commonly supplied as a crystalline mass, in flake form, or as a fused solid.
Sodium and potassium form KNa 2 and NaK. NaK is 40–90% potassium and it is liquid at ambient temperature. It is an excellent thermal and electrical conductor. Sodium-calcium alloys are by-products of the electrolytic production of sodium from a binary salt mixture of NaCl-CaCl 2 and ternary mixture NaCl-CaCl 2-BaCl 2.
Gilbert N. Lewis introduced the concepts of both the electron pair and the covalent bond in a landmark paper he published in 1916. [1] [2] MO diagrams depicting covalent (left) and polar covalent (right) bonding in a diatomic molecule. In both cases a bond is created by the formation of an electron pair.
He introduced the Lewis notation or electron dot notation or Lewis dot structure, in which valence electrons (those in the outer shell) are represented as dots around the atomic symbols. Pairs of electrons located between atoms represent covalent bonds. Multiple pairs represent multiple bonds, such as double bonds and triple bonds. An ...
For example, boron trifluoride (BF 3) and ammonia (NH 3) form an adduct or coordination complex F 3 B←NH 3 with a B–N bond in which a lone pair of electrons on N is shared with an empty atomic orbital on B. BF 3 with an empty orbital is described as an electron pair acceptor or Lewis acid, while NH 3 with a lone pair that can be shared is ...
2 symmetry, with almost eclipsed with a 16° O-S-S-O torsional angle. In the dihydrated form (Na 2 S 2 O 4 ·2H 2 O), the dithionite anion has gauche 56° O-S-S-O torsional angle. [1] A weak S-S bond is indicated by the S-S distance of 239 pm, which is elongated by ca. 30 pm relative to a typical S-S bond. [2]
BF 3 + OMe 2 → BF 3 OMe 2. Both BF 4 − and BF 3 OMe 2 are Lewis base adducts of boron trifluoride. Many adducts violate the octet rule, such as the triiodide anion: I 2 + I − → I − 3. The variability of the colors of iodine solutions reflects the variable abilities of the solvent to form adducts with the Lewis acid I 2.