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  2. Cation-anion radius ratio - Wikipedia

    en.wikipedia.org/wiki/Cation-anion_radius_ratio

    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 ...

  3. Pauling's rules - Wikipedia

    en.wikipedia.org/wiki/Pauling's_rules

    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. [5]

  4. Ionic radius - Wikipedia

    en.wikipedia.org/wiki/Ionic_radius

    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 .

  5. Salt (chemistry) - Wikipedia

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

    In chemistry, a salt or ionic compound is a chemical compound consisting of an assembly of positively ... Critical radius ratio Madelung constant MX: 8:8: entirely ...

  6. Atomic radii of the elements (data page) - Wikipedia

    en.wikipedia.org/wiki/Atomic_radii_of_the...

    For more recent data on covalent radii see Covalent radius. Just as atomic units are given in terms of the atomic mass unit (approximately the proton mass), the physically appropriate unit of length here is the Bohr radius, which is the radius of a hydrogen atom. The Bohr radius is consequently known as the "atomic unit of length".

  7. Cubic crystal system - Wikipedia

    en.wikipedia.org/wiki/Cubic_crystal_system

    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 ...

  8. Critical radius - Wikipedia

    en.wikipedia.org/wiki/Critical_radius

    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.

  9. Atomic radius - Wikipedia

    en.wikipedia.org/wiki/Atomic_radius

    Hence lutetium is in fact slightly smaller than yttrium, hafnium has virtually the same atomic radius (and chemistry) as zirconium, and tantalum has an atomic radius similar to niobium, and so forth. The effect of the lanthanide contraction is noticeable up to platinum ( Z = 78), after which it is masked by a relativistic effect known as the ...