The shell closest to the nucleus is called the a. full shell b. inner or c. shell nuclear shell

inner shell

Explanation:

The shell closest to the nucleus is called inner shell. e.g K shell is more closest to the nucleus it consist of one sub shell 1s. The second shell L is the next to the k shell and it consist of two sub shell 1s and 2p.

The electrons present in outer most shell or higher energy level are valance electrons, while the electron present in inner most shell or lower energy level are called core or inner electrons.

The valance electrons take part in bonding. The valance electrons form either a ionic bond or covalent bond during chemical reaction. These electrons involve in bond making and bond breaking process. while inner electrons do not take part in bonding. The hold of nuclear attraction on the inner electrons is most as compared to the valance electrons.

Example:

Consider the example of carbon. The atomic number of carbon is six.

Electronic configuration:

1s² 2s² 2p²

In this electronic configuration we can see that two electrons are present in 1s shell these are called core electrons. The electrons present in 2s and 2p are called valance electrons and take part in chemical reaction.