Which type of element is most likely to gain electrons when it forms a bonds?

The nonmetals.

The nonmetals gain electrons when it form bonds

Non-metals

Non-metals tend to gain electrons to attain Noble Gas configurations. The have relatively high Electron affinities and high Ionization energies. Metals tend to lose electrons and non-metals tend to gain electrons, so in reactions involving these two groups, there is electron transfer from the metal to the non-metal.-Google