Question

What Is the kernel?

Answer 1

Kernel refers to the nucleus and all of the electrons, except those in the valance (outer) shell.
Positive ions surrounded and held togerher by sea of free electrons in metallic solids, these are called kernels.

Kernel electrons are those which are not present in valence shell.

Kernel = Nucleus + inner electrons.

Physical meaning of kernel is ‘small part of something’

When we explain bonding in atoms, we don't stress on kernel electrons.

In terms of bonding only use of kernel electron is that it has no use. However, they are present in atom and gives characteristics properties to that atom.

Hope it makes you clear.