The official minimum connection time for domestic to international, on Delta, at Atlanta is 60 minutes. So it looks like you have plenty of time. But, as has been noted, you cannot predict delays. If missing that flight to Santiago would be a disaster from your point of view (e.g. cause you to miss a vital meeting) you could consider taking an earlier flight to Atlanta.

Also if your flights are on one ticket then Delta will accommodate you in the event of a missed connection. If not, the problem of moving onto another flight will be yours and could be expensive.