As a trend or pattern, the atomic radius decreases as you go left to right across the period, but increases as you go down a particular group.
The model after John Dalton's was J.J Thompson's plum podding model in 1897, which described electrons as dots or raisins(if you will) in a circle shaped pudding that was entirely positive using a Cathode Ray Tube(shot cathode rays between magnets). The model after that is the Niels Bohr model in 1913, which depicts atoms like positively charged center called the nucleus with negatively charged particles called electrons in a shell or cloud.
The violet light has the shortest wavelength.
