Question

The atomic number of beryllium is 4 while that of oxygen is 8. Write down the electronic configuration of the two and deduce their valency from the same????

Answer 1

electronic configuration of beryllium=2,2
2 electrons are in the outermost shell so to complete its duet it will donait 2 electrons.
hence its valency is 2

electronic configuration of oxygen=2,6
6 electrons are in the outermost shell and to complete its octet it needs 2 electrons.
hence its valency is -2.

hope it helps you

Answer 2

"The electronic configuration of beryllium is $1{ s }^{ 2 }2{ s }^{ 2 }$and the electronic configuration of oxygen is $1{ s }^{ 2 }2{ s }^{ 2 }2{ p }^{ 4 }$

And therefore, valance electrons of Oxygen is 4 and Beryllium is 2.

The electron in the outer shell is known as valence shell electron which helps in formation of chemical bond.

Atomic number of Beryllium is 4.

Atomic number of Oxygen is 8."