| A | B |
|---|
| Hund's rule | lowest-energy arrangement of electrons in a subshell is obtained by putting electrons into separate orbitals of the subshell before pairing electrons |
| photons | packets/quanta of electromagnetic energy |
| hertz | the SI unit of frequency |
| Pauli exclusion principle | an atomic orbital can hold no more than two electrons |
| quantum | the amount of energy required to move an electron from its present energy level to the next higher one |
| quantum mechanical model | the modern description of the location and energy of electrons in an atom |
| Aufbau principle | this principle states that electrons enter orbitals of lowest energy first |
| wavelength | the distance between two adjacent crests of an electromagnetic wave |
| atomic emission spectrum | is produced by passing the light emitted by an element through a prism |
| photoelectrons | these are sometimes produced when light shines on metals |
| amplitude | the wave’s height from zero to the crest |
| atomic orbital | the region of space in which there is a high probability of finding an electron |
| electromagnetic radiation | radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, gamma rays |
| energy levels | the fixed energies an electron can possess |
| frequency | the number of wave cycles to pass a given point per unit of time |
| ground state | the lowest possible energy an electron may posses in an atom |
| Heisenberg uncertainty principle | it is impossible to know exactly both the velocity and position of a particle at the same time |
| spectrum | sunlight passing through a prism separate into different frequencies of light represented by different colors |
| electron configurations | the ways in which electrons are arranged in various orbitals around the nuclei of atoms |
