Hello everyone
I have a question about the volume of the compound. For example, the structure of perovskite ABO3, what useful information can I get based on its chemical formula volume (VABO3)?
Taking perovskite as an example, the chemical formula volume is the volume occupied by these 5 atoms in the crystal
There are various concepts around which derive simple properties of compounds from increments characteristic for the contributing atoms/ions (or group of atoms). Simply a variant of "rule of mixing". Most well known are atomic/ionic radii which allow more or less accurate prediction of atomic distances and crystallographic parameter (e.g. via the hard sphere model). Simply said, distances are certain sums of radii within the constraints of the 3d structure. All this is closely related with Vegard's rule. Less known is use of volume increments associated atoms and group of atoms (molecules). One school is prediction of molar volumes of metallic solid solutions and intermediate phases by Zen (look for Zen's law). Similar ideas were also proposed mainly for nonmetallic materials by Biltz (Raumchemie fester Stoffe, originally not so much to crystal structure but to densities, if I recall correctly). Basically the volume is a sum of the volume increments of the constituents. Note that the predictions made on basis of distance increments or volume increments are mathematically incompatible but the results are usually very close. By searching for Biltz' law or Zen's law in association with perovskites you may find out whether somebody already has made such considerations.
A chemical formula tells us the number of atoms of each element present in a compound.One can derive molar mass, structure, properties from chemical formula.
Madhukar Baburao Deshmukh
I would like to see how we derive the structure from the chemical formula. Sometimes it's comical, like CuS (covellite).
Otherwise, terminologically, the compound has no volume. The volume has a unit cell that contains a number of formula units (Z). The correlation between chemical composition and cell volume (V) or V/Z may work, but only for structurally similar compounds. For example, you can compare V / Z for CaO and Ca (OH)2.
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