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.
1 The electrons of an atom revolve around the nucleus in orbits. 2  These orbits are associated with definite energies and are also called energy shells or energy levels. 3  Thus, the electrons do not continuously lose energy as they travel in a particular orbit.