1 4,18. 2  Shingles in caused by the same virus that causes chickenpox-varicella-zoster virus. 3  Shingles is a painful infection of the nerve supplying an area of skin and is accompanied by a localised skin rash.
The electrons on the outermost energy level of the atom are called valence electrons. The valence electrons are involved in bonding one atom to another. The attraction of each atomâs nucleus for the valence electrons of the other atom pulls the atoms together.
The orbit around the nucleus within which the electron rotate is called shells or Energy levels. Each discrete distance orbit from the nucleus corresponds to a certain energy level. The electron which rotates in the lowest orbit has lowest energy level and in the outermost orbit, electrons have higher energy levels. Hence energy levels increase as the distance from the nucleus increases.