Hi Hanin. This does relate to electronegativity in a way since the halogens in group 17 want to "gain" an electron to satisfy their octet and fill the p subshell (6 electrons.) Then they will become stable like the noble gases in group 8. So the final subshell for the halogens should be the p subshell. The halogens contain 5 electrons in this subshell. You can go through the periods (rows) and groups (columns) to find the electron configuration for the elements. For example, the structure of Fluorine is 1s2-2s2-2p5 and the number of electrons = 9, same as the atomic number in the table.
