What is represented by the dots in a lewis electron-dot diagram ofan atom of an element in period 2 of the periodic table?
(1) the number of neutrons in the atom(2) the number of protons in the atom(3) the number of valence electrons in the atom(4) the total number of electrons in the atom

The number of Valence electrons are shown so that one can clearly see the electron transfer or sharing that may take place between the atoms.

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.