Among the last frontiers to be mapped was/were the

Polar regions.

Explanation:

fh gyu jfh fluffy y gyu gyu gyu gyu fyuf hug uhfyu fungus f jy hug fy iffy ya guy fyuf usf us gyu gyu uyfuy fyu gyu fyu fyuf you fyu fyu uyf fyu fyu jy uyf uyf guys y fyuyg giygy iuf giu fyi iuf ya ffui fui hive guy gyu giu iuf ya giu jyu

because the two particles have an equal charge, the charges will cancel out and give the atom an overall charge of 0. so, if at atom has 35 protons in the nucleus, we could expect it to have 35 electrons orbiting that nucleus.