Search results
Results From The WOW.Com Content Network
In condensed matter physics and inorganic chemistry, the cation-anion radius ratio can be used to predict the crystal structure of an ionic compound based on the relative size of its atoms. It is defined as the ratio of the ionic radius of the positively charged cation to the ionic radius of the negatively charged anion in a cation-anion compound.
An octahedron may then form with a radius ratio greater than or equal to 0.414, but as the ratio rises above 0.732, a cubic geometry becomes more stable. This explains why Na + in NaCl with a radius ratio of 0.55 has octahedral coordination, whereas Cs + in CsCl with a radius ratio of 0.93 has cubic coordination.
The tetrahedral void is smaller in size and could fit an atom with a radius 0.225 times the size of the atoms making up the lattice. An octahedral void could fit an atom with a radius 0.414 times the size of the atoms making up the lattice. [1] An atom that fills this empty space could be larger than this ideal radius ratio, which would lead to ...
Critical radius is the minimum particle size from which an aggregate is thermodynamically stable. In other words, it is the lowest radius formed by atoms or molecules clustering together (in a gas , liquid or solid matrix) before a new phase inclusion (a bubble, a droplet or a solid particle) is viable and begins to grow.
A dense packing of spheres with a radius ratio of 0.64799 and a density of 0.74786 [22] Many problems in the chemical and physical sciences can be related to packing problems where more than one size of sphere is available.
Ionic radius, r ion, is the radius of a monatomic ion in an ionic crystal structure. Although neither atoms nor ions have sharp boundaries, they are treated as if they were hard spheres with radii such that the sum of ionic radii of the cation and anion gives the distance between the ions in a crystal lattice .
According to the radius ratio rule, this structure is more likely to be formed if the cation is somewhat smaller than the anion (a cation/anion radius ratio of 0.414 to 0.732). The interatomic distance (distance between cation and anion, or half the unit cell length a ) in some rock-salt-structure crystals are: 2.3 Å (2.3 × 10 −10 m) for ...
The Royal Game of Ur, dating from 2600 BC, was played with a set of tetrahedral dice. Especially in roleplaying, this solid is known as a 4-sided die, one of the more common polyhedral dice, with the number rolled appearing around the bottom or on the top vertex. Some Rubik's Cube-like puzzles are tetrahedral, such as the Pyraminx and Pyramorphix.