Write an informal definition of half-life.

the time required for the activity of a substance taken into the body to lose one half its initial effectiveness. Informal. a brief period during which something flourishes before dying out.

hope this helps ^^

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.