If i had a mixture of salt, sand, and iron filings i could separate the mixture by …

Okay to separate this mixture you will have to first use a magnet because the magnet will attract the iron filings out of the sand then you will remain with the sand and salt.

Next step is to add water to the sand and salt mixture the salt will dissolve in the water and the sand will not forming a heterogeneous mixture.Then using the method of filtration you can separate the sand from  the salt solution leaving the salt solution

 To separate the salt from the water use the method of evaporation this will enable you to get back the salt 

In the end you should beable to have the sand,salt and iron filings separate.

Hope this was helpful to you.

Happy New Years !!! May your year be prosperous 

Outermost (valence) electrons

What do you mean by that? like the contents? the thc level?