A certain metal M crystallizes in a lattice described by a face-centered cubic (fcc) unit cell. The lattice constant a has been measured by X-ray crystallography to be 526.pm. Calculate the radius of an atom of M. Be sure your answer has the correct number of significant digits, and be sure it has the correct unit symbol.

They are all full and don't need any more electrons in there outer shell.

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant.