Calculating Density of SiO2 in the Periodic Table

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Discussion Overview

The discussion centers on the calculation of the density of silicon dioxide (SiO2) using the known densities of its constituent elements, silicon (Si) and oxygen (O). Participants explore the complexities involved in determining the density of a compound, particularly in relation to its crystal structure and other properties.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants suggest that the density of SiO2 cannot be calculated solely from the densities of silicon and oxygen due to the variability in crystal structures that SiO2 can form.
  • Warren emphasizes that additional information, such as bond angles, bond lengths, and crystal organization, is necessary to calculate the density of SiO2.
  • There is a query about whether it is possible to calculate the density of SiO2 using the cell vectors of the unit cell and the formula units per unit cell, indicating a potential method for calculation.
  • Another participant mentions that the density of SiO2 is commonly listed in material property tables, suggesting that empirical data may be more accessible than theoretical calculations.
  • Discussion also touches on a separate topic regarding the creation of an alloy film from aluminum (Al) and titanium (Ti), with uncertainty expressed about the outcome based on varying fluxes of the elements.
  • Warren notes that the outcome of the alloy film would depend on numerous parameters, including deposition conditions, and suggests that advanced computational methods would be required for accurate predictions.

Areas of Agreement / Disagreement

Participants generally disagree on the feasibility of calculating the density of SiO2 from the densities of its elements alone. There is no consensus on the specific additional values required for such a calculation, and the discussion remains unresolved regarding the exact methodology.

Contextual Notes

Limitations include the dependence on specific crystal structures and the need for detailed knowledge of atomic arrangements, which are not provided in the discussion. The complexity of the alloy film formation process is also noted, with various influencing factors remaining unspecified.

physicist888
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in the periodic table we have the density of each element ( density(Si) = 2.33), density(O)=1.429). i wonder how we could calculate the density of SiO2 ?
 
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It isn't possible to simply calculate it, knowing only the densities of the two pure elements. Each compound can form crystals, sometimes many different kinds of crystals, and each will have its own density.

- Warren
 
an how we could calculate it? is there an equation? the density of SiO2 = ?
 
Ti-Al ??flux?

to creat a film of alloy Al and Ti we use to flux of each element and a substrat.
if the flux of Al is double of that of Ti, then we obtain an alloy on the substrat AlTi or what?
 
physicist888 said:
the density of SiO2 = ?

Try google. Also, SiO2 is so common that the density is listed in most tables of material properties.
 
i know the value, but i need to know how to calculate it
 
Didn't I already say that you cannot calculate it only by knowing the density of Si alone and O alone?

- Warren
 
then which other values do we need to calculate it??
 
You need to know its bond angles and lengths, crystal organization, etc.

- Warren
 
  • #10
and you don't know about the other question??
((to creat a film of alloy Al and Ti we use to flux of each element and a substrat.
if the flux of Al is double of that of Ti, then we obtain an alloy on the substrat AlTi or what?))
 
  • #11
Also almost impossible to answer. What kind of film you end up will depend on many different parameters (including deposition parameters such as temperature, pressure etc). My guess would be that you would end up with a granular film with grains of Al and Ti (Al tends to form small grains so the film might even be quite dense).
But again, that is only a guess.
In order to calculate something like that you would need a reasonably good supercomputer and extensive knowledge of DFT calculations
 
  • #12
would it be possible to calculate the density of SiO2 just from the following:

(1) Cell vectors of Unit cell (ie. Volume)
(2) Formula Units per unit cell. (ie. Mass of the atoms in the unit cell)
 

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