By observing given data which group elements can easily forms negative ions with net charge to be one?

VII A group elements have high electro negative nature. Due to this reason VIIA group elements can form stable anion by gaining one electron from other atoms of elements. Ex:

$\text{Fluorine,(F) }\to \text{Z}=9;\text{\hspace{0.17em}\hspace{0.17em}Electron\hspace{0.17em}configuration }1{\text{s}}^{2}2{\text{s}}^{2}2{\text{p}}^5$

$\text{F\hspace{0.17em}\hspace{0.17em}+\hspace{0.17em}}{e}^{-}\to {\text{\hspace{0.17em}F}}^{-}\left(1{\text{s}}^{2}2{\text{s}}^{2}2{\text{p}}^6\right)$