Suppose that 273 g of one of the substances listed above displaces 26 ml of water. what is the substance?

The unknown substance is silver. I don't see a list of available substances, but let's see if there's something reasonable available that will match. First, let's calculate the density of the unknown substance. Density is mass per volume, so 273 g / 26 mL = 10.5 g/mL Looking up a list of elements sorted by density, I see the following: 10.07 Actinium 10.22 Molybdenum 10.5 Silver 11.35 Lead And silver at 10.5 g/ml is a very nice match for the unknown substances' density of 10.5 g/ml.

I dont see your list anywhere, but if silver is on your list,, that would be the answer, 

It won't lose or gain electrons if it's a covalent bond it shares the electrons with another atom or atoms. if it is an ionic bond it will lose the 3 electrons on the outer shell and become a positively charged ion.  credit goes to @sunshinebaby of answers.yahoo.com.