Chlorine in group 17 in the periodic table and includes halogens (also fluorine, bromine, and iodine)
Electron configuration of Cl : [Ne] 3s² 3p⁵
From this configuration, it can be seen that to obtain stability like the noble gas Ar - [Ne] 3s² 3p⁶, Chlorine will need one more electron so that its configuration is the same as Ar( become anion-Cl⁻)
Then it is said that Cl is reactive
And the Cl element is included in the non-metal group because it attracts electrons (electronegative)
The elements that include non-metals are halogens, noble gases, and 7 elements H, C, N, O, P, S, Se.