how do you find atomic mass ?

Question

using fractional abudance of three isotopes and their average atomic mass

the periodic table won't help because its a made up element

Answer 1

The relative atomic mass (also known as atomic weight and average atomic mass) is the average of the atomic masses of all the chemical element's isotopes as found in a particular environment, weighted by isotopic abundance. Periodic tables usually list these with reference to the local environment of Earth's crust and atmosphere. An uncertainty in parenthesis is often included. For artificial elements the nucleon count of the most stable isotope is listed in brackets as the atomic mass.

See: http://en.wikipedia.org/wiki/Atomic_mass
For more information

Answer 2

type atomic mass into the wikipedia search and check it out.

Answer 3

what element is it? and atomic mass is the # of protons plus the number of neutrons...while at the same time protons= the # of electrons..so you can add the # of electrons(or protons) to the # of neutrons.