Can compounds have a higher density than their component elements?

[PolarisNorth]

I am doing an experiment to compare the force of buoyancy on an object by particular mixtures of saltwater. To do so, I need to first find the density. I do not have any special device for determining the density, so I decided to record my given information and solve for it using the definition of density=mass/volume.

I have a general question about an issue that I need clarification on:
I found the total mass of X mL of saltwater, but I'm not sure what volume is referring to.
Is it referring to the displaced volume on the object or just how many mL of saltwater I have?

Thank you!

 

[Doc Al]

To find the density, you need the volume of the X ml of saltwater whose total mass you found:

Density = (mass of stuff)/(volume of stuff)

 

[PolarisNorth]

Thank you. That cleared it up for me.

 

[Researcher X]

Since that question has been answered and I don't think it's worth making another thread on density; I'll ask here.

Can compounds be denser than their component elements? Could we make something stable that was denser than Osmium? Structure varies density, but perhaps the atoms in elements are already as densely packed as they can be.