In a solid metal sample, how are valence electrons distributed? A)

Valence electrons are shared among many metal ions.

B)

Valence electrons are unequally distributed, giving some metal ions positive charge and some metal ions negative charge.

C)

Valence electrons are localized to each metal atom, giving it a neutral charge.

D)

Valence electrons are shared between neighboring metal atoms to form covalent bonds.

it is the minimum amount of material needed to sustain a fission reaction.

critical mass is the minimum amount of fissionable material that must be assembled for a sustained fission reaction to take place. although two to three neutrons are produced for every fission, not all of these neutrons are available for continuing the fission reaction. if the conditions are such that the neutrons are lost at a faster rate than they are formed by fission, the chain reaction will not be self-sustaining.   at the point where the chain reaction can become self-sustaining, this is referred to as critical mass.