Chemistry - Except pure alloys, are there any compounds with more metal elements proportion of atoms than nonmetal elements in proportion of atoms?

Solution 1:

There are some rare but very interesting cases in which two metals react when mixed instead of forming an alloy, creating a non-metallic compound made only with metal atoms. Examples are caesium auride ($\ce{CsAu}$), caesium platinide ($\ce{Cs2Pt}$) and several barium platinides ($\ce{BaPt}$, $\ce{Ba2Pt}$, $\ce{Ba3Pt2}$, and possibly others), all of which best described as ionic salts rather than alloys. These are a remarkable consequence of relativistic effects in heavy atoms.

Solution 2:

In addition to the answers by Nicolau and DrMoishe.

Most prominent examples are the binary oxides of the alkali metals $\ce{A2O}$: lithium oxide $\ce{A~=~Li}$, sodium oxide $\ce{A~=~Na}$, potassium oxide $\ce{A~=~K}$, rubidium oxide $\ce{A~=~Rb}$ and caesium oxide $\ce{A~=~Cs}$.
Of course there are also higher homologs of these compounds like lithium sulfide $\ce{Li2S}$.

Especially for rubidium and caesium there are also a number of suboxides, i.e. $\ce{A9O2}$ and others. This is a whole class of compounds whith a rich variety.

There are also the nitrides of the alkali and earth alkali metals, e.g. lithium nitride $\ce{Li3N}$ and magnesium nitride $\ce{Mg3N2}$.

There are a couple of phosphides known, that fit your description, e.g. $\ce{K3P}$, $\ce{K4P3}$, $\ce{K5P4}$. These compound are also known from transition metals, like $\ce{Cu3P}$ or $\ce{Ni5P2}$.

Like the above, there are also some very common carbides, like aluminium carbide $\ce{Al4C3}$.

And I am very certain, there are many more.

Solution 3:

Sure, e.g. sodium aluminate, Na2Al2O4 (anhydrous formula), is a common chemical (it's the "gray stuff" on aluminum dishware cleaned in an automatic dishwasher with alkaline detergents).

Solution 4:

Petzite, $\ce{Ag3AuTe2}$, is an uncommon telluride containing mineral that seems to fit the bill.

Sodium oxide $\ce{Na2O}$ is well known, as is potassium oxide, rubidium oxide, etc.

Some one should write a parser and see if this list from Wikipedia has any more examples. I didn't see any that weren't already mentioned here on a quick skim.