what is the skeletal structure of the atom?
We cannot write the skeletal structure to an atom but to a molecule or a compound where skeletal structure has all atoms connected to center atom with single bonds.
Connect the atoms to the central atom with a straight line representing a bond between the two atoms. The central atom can have up to four other atoms connected to it. This is called the skeletal structure.
In CO2 molecule, the center atom is C and the skeletal structure is drawn as
O—C—O. This structure is used while writing Lewis structure for a molecule.