Consider the following energy levels of a hypothetical atom:
-1.0 x 10^-19j
-5.0 x 10^-19j
-10 x 10^-19j
-15 x 10^-19j
(a) what is the wavelength of a photon needed to excite an electron from e1 to e4? (b) what is the energy (in joules) a photon must have in order to excite an electron from e2 to e3? (c) when an electron drops e3 level to the e1 level, the atom is said to undergo emission. calculate the wavelength of the photon emitted in this process.

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.