What does it mean for the energy levels in an atom to be quantized? Describe how this affects where electrons can be found.

Energy of an electron is quantinized means the electrons can possess only specific individually separated values.

These energy levels are stable and are stationary along with different energy value.  The electron remains in the state until energy is absorbed or released.

The electrons absorb energy when it moves from lower energy state to higher energy state. The electrons lose energy when it moves from higher energy state to lower energy state and thus emit radiations corresponding to the energy gap and is called as quanta.

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.