Energy+Changes+in+an+Atom

=Energy Changes in an Atom (Delta E)=



The most important concept of energy change within an atom is that an atom can only absorb or emit energy of certain intervals, called a quantum. A quantum is the smallest possible amount of energy that can be absorbed or emitted. Planck first proposed this theory in 1900. The energy of one quantum can be calculated using Planck's constant, h = 6.626 x 10 ^ -34, and the following equation:

Since energy can not be divided any smaller than one quantum, the calculated amount of energy must always be in intervals of one quantum. This theory was later proved correct and Planck awarded a Nobel prize in 1918. This theory helped to advance many other ideas and theories, including Einstein's photoelctric effect and Bohr's work on the electromagnetic spectrum.

The next big concept governing energy change is electron shells. Each atom has 7 shells which correspond to energy levels at ground state (the state when an atom is at it's lowest amount of energy). Also at ground state, the electrons are located within the shells closest to the nucleus. However, if the atom absorbs energy, or gets "excited," the electrons "jump" into the higher shells, going further away from the nucleus. This can only happen when the atom absorbs energy. In contrast, when an atom emits energy, the electrons return to the lower shells, returning close to the nucleus and reverting back to ground state. The energy gets emitted in the form of electromagnetic radiation, or light.

Lastly, each emission correlates to a certain energy level and wavelength. For each jump between level, like going from 7 to 3 or 6 to 1, radiation with a certain wavelength is produced. The combination of possible energy changes produces a signature line spectrum unique to each substance. This is the basis of flame tests.

Sources Brown, LeMay, and Bursten: //Chemistry, the Central Science// [|http://www.thespectroscopynet.com]

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