ATOMIC SPECTRA
Studies of atomic spectra confirmed the basic periodic arrangement
of elements as set out by Mendeleef and helped to develop this into the
modem table shown in the figure in the inside cover of this book.
When atoms of an element are excited, for example in an electric
discharge or by an electric arc, energy in the form of radiation is
emitted. This radiation can be analysed by means of a spectrograph
into a series of lines called an atomic spectrum. Part of the spectrum
oi hydrogen is shown in Figure 1.4. The lines shown are observed in
the visible region and are called the Balmer series after their