Question

Both helium (He) and beryllium (Be) have two valence electrons. Whereas He represents a noble gas element, Be does not. Assign reason.​

Answer 1

Answer:

Atomic number of Helium is 2 so it has two electrons in first shell and therefore it is a noble gas. Atomic number of Beryllium is 4 so it has two electrons in first shell and in second shell it need 8, so it can donate its 2 electrons an therefore it has valency 2 and so it is not a noble gas.