Because metallic bonds involve all of the metal atoms in a piece of metal sharing all of their valence electrons with "delocalized" bonds.
I'm not too sure but I think it's nuclear decay
Answer:No, it doesn't move easily downward because it will try to resist the movement ,due to a resistance force of inertia that it possess at rest.
Explanation:when an object has higher or larger mass it tends to resist any motion given to it unlike the one with lower mass.
The larger the mass the more resistance force an object has.
It hardens because you are pressing it against something.