Line Spectra:

Line spectra are acquired from individual atoms which are well separated within a gaseous sample of components. The atomised sample of the element is subjected to a flame, plasma, an electric arc or spark whereby the constituent atoms are excited to higher orbitals. For instance, in case of sodium atom, single outer electron in the 3s orbital could be excited to higher orbitals. The excited state being unstable and short lived, returns to the ground state through the emission of a photon. The emission from the first excited state (3p) of sodium is responsible for the yellow color emission at 589.6 nm of the flame while sodium salts are introduced within it. Other excited states corresponding to 4p and 5p levels provides emissions at 330.6 nm and 285.3 nm correspondingly in the ultraviolet region. A flame emission and atomic emission spectroscopic methods are based on this phenomenon and are meaningful for qualitative and quantitative measurement of atoms. You would learn about these within the third block of the course.