Why are metallic compounds solid at room temperature?
Well, if you mean metals, most are....
But caesium and mercury are certainly room temperature LIQUIDS. That metals exist in condensed phases under standard conditions is a consequence of metallic bonding, which is a non-molecular force of interaction, and is commonly described as
And as to metallic compounds, well metals in general are REDUCING materials...i.e. they are ELECTRON-RICH. And thus they likely to form ionic compounds with ELECTRON-POOR oxidants from the RIGHT of the Periodic Table as we face it....to give metal SALTS, in which the metal has been OXIDIZED, and the non-metal has been REDUCED....and a few examples..