What is the total number of valence electrons in the peroxydisulfate, ${\mathrm{S}}_2{\mathrm{O}}_8^{2-}$ , ion ?

how many valence electrons are present in the peroxydisulphate ion overall ion ${\mathrm{S}}_2{\mathrm{O}}_8^{2-}$ is 62. 

$2\left(6\right)+8\left(6\right)+2=12+48+2=62$.