Question

Why carbon is unstable

Answer 1

Hi there !!

-->Carbon is the element which is unstable here.

-->This is because its shells are not filled.

-->Its atomic no: is 6.

--> No : of electrons is also 6.

-->Its electronic configuration is 2 ,4

-->Thus it needs to lose 4 electrons to combine with another element

-->Its valency is 4

--->Therefore it is unstable

Answer 2

Let's see we have an atom of Carbon, i.e. $_{6}^{12}C$
So, it's atomic number is 6.
Hence, it has 6 protons and 6 electrons.

What is the electric configuration of Carbon?
It has 2 electrons in the K-Shell
and 4 in the L-Shell,
∴ it is 2,4

But, according to the Octet rule, which simply means that an atom should have 8 (or a multiple of 8) electrons in its outer shell (Chemists have given it a fancy name called "Valence Shell").
But Carbon has only 4 electrons in its 'Valence Shell'.
To complete its octet, Carbon tries to give away these 4 electrons.
And it does it by reacting with other atoms (with incomplete valence shells).

Thus Carbon is reactive.