Question

Both helium and beryllium have two electrons in the Valence shells. Helium is a noble gas whereas beryllium is a metal, justify... Plzz answer...Urgent

Answer 1

the number of electrons in the valent shell of both the elments are same but the number of shells are not same.helium valent shell is 1 which so close to the nucleus and experiences higher force of attraction they do not take part in reaction.Thus it is a noble.beryllium valent shell is 2 though it is close to nucleus it undergo reaction and form covalent bonds.

Answer 2

helium is a chemical element with atomic number 2.as the k  shell is completely filled and it has no charge.so it is a noble gas.

beryllium is a chemical element with atomic number 4.it's k shell is completely filled but it's l shell has 2 electrons but to become valence it needs 6 more electrons.so beryllium is a metal and not a noble gas.