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.
Electrons have the lowest energy when closest to the nucleus. Under resting conditions, the electrons are in the lowest possible energy level called. ground state. When atom absorbs a quantum of energy, it causes the electron to jump to a higher energy level called the excited state. Excited atom is energetically unstable, so electron will fall back down very rapidly and energy will given off in the same amount as absorbed but now in the form of a photon of light.