A. A main group element with the valence electron configuration 4s2 is in periodic group ( ). It forms a monatomic ion with a charge of ( ). B. A main group element with the valence electron configuration 3s23p5 is in periodic group ( ). It forms a monatomic ion with a charge of ( ).

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.

it is the most commonly accepted one