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The same crystal structure is found in numerous ionic compounds with formula AB 2, such as CeO 2, cubic ZrO 2, UO 2, ThO 2, and PuO 2. In the corresponding anti-structure, called the antifluorite structure, anions and cations are swapped, such as Be 2 C.
The fluorite structure refers to a common motif for compounds with the formula MX 2. [1] [2] The X ions occupy the eight tetrahedral interstitial sites whereas M ions occupy the regular sites of a face-centered cubic (FCC) structure. Many compounds, notably the common mineral fluorite (CaF 2), adopt this structure.
Lewis structure of a water molecule. Lewis structures – also called Lewis dot formulas, Lewis dot structures, electron dot structures, or Lewis electron dot structures (LEDs) – are diagrams that show the bonding between atoms of a molecule, as well as the lone pairs of electrons that may exist in the molecule.
Lewis structures (or "Lewis dot structures") are flat graphical formulas that show atom connectivity and lone pair or unpaired electrons, but not three-dimensional structure. This notation is mostly used for small molecules. Each line represents the two electrons of a single bond. Two or three parallel lines between pairs of atoms represent ...
The structure of calcium fluoride CaF 2. [13] Fluorite crystallizes in a cubic motif. Crystal twinning is common and adds complexity to the observed crystal habits. Fluorite has four perfect cleavage planes that help produce octahedral fragments. [14] The structural motif adopted by fluorite is so common that the motif is called the fluorite ...
The same crystal structure is found in numerous ionic compounds with formula AB 2, such as ceria (CeO 2), zirconia (cubic ZrO 2), uranium dioxide (UO 2). In the corresponding anti-structure, called the antifluorite structure, anions and cations are swapped, such as beryllium carbide (Be 2 C) or lithium oxide (Li 2 O), potassium sulfate (K 2 SO 4).
[3] [7] Lewis was best known for his discovery of the covalent bond and his concept of electron pairs; his Lewis dot structures and other contributions to valence bond theory have shaped modern theories of chemical bonding.
The most common Lewis bases are anions. The strength of Lewis basicity correlates with the pK a of the parent acid: acids with high pK a 's give good Lewis bases. As usual, a weaker acid has a stronger conjugate base. Examples of Lewis bases based on the general definition of electron pair donor include: simple anions, such as H − and F −