A sodium atom in an unexcited state has the structure 1s22s22p63s1, but within the flame there will be all sorts of excited states of the electrons. Sodium's familiar bright orange-yellow flame color results from promoted electrons falling back from the 3p1 level to their normal 3s1 level. The exact sizes of the possible jumps in energy terms vary from one metal to another. That means that each different metal will have a different pattern of spectral lines, and so a different flame color. Flame colors are produced from the movement of the electrons in the metal ions present in the compounds. For example, a sodium ion in an unexcited state has the electron configuration 1s22s22p6. When heated, the electrons gain energy and can be excited into any of the empty higher-energy orbitals—7s, 6p, 4d, or any other, depending on the amount of energy a particular electron happens to absorb from the flame. Because the electron is now at a higher and more energetically unstable level, it falls back down to the original level, but not necessarily in one transition. The electron transitions which produced lines in the visible spectrum involved atoms rather than ions.