both helium and beryllium have two electrons in the valence shell. helium is a noble gas whereas beryllium is a metal. justify

both helium and beryllium have two electrons in the valence shell. hel

1.	both helium and beryllium have two electrons in the valence shell. helium is a noble gas whereas beryllium is a metal. justify
Answer» Helium has 2 electrons in the first shell which can accomodate a maximum of 2 electrons. As the shell is completely FILLED, Helium is STABLE. Beryllium has 2 electrons in the second shell which can accomodate a maximum of 8 electrons. As the shell is not completely filled, Beryllium is not stable. Beryllium can lose two electrons to get a stable noble GAS CONFIGURATION. Thus it has an electron DONATING nature. Hence it behaves as a metal.