The fixed amount of energy that a system described by quantum mechanics, such as a molecule, atom, electron, or nucleus, can have.
- ‘This means that an atom with eight electrons in its outermost energy level is very stable.’
- ‘This higher energy level allows X-ray beams to pass straight through most of the soft material in the human body.’
- ‘When an electron falls from a higher energy level to a lower energy level, a photon is given off.’
- ‘For instance, photons will share a particular energy level in a laser.’
- ‘An electron in a lower energy level is both closer to the nucleus and has fewer electrons between itself and the nucleus.’
We take a look at several popular, though confusing, punctuation marks.