The Nationals took an 8-2 lead through four innings and coasted past the struggling Padres, who have lost seven in a row.
Gio Gonzalez (6-3) was the beneficiary of the early onslaught, surviving 6 2/3 innings to get the win. He allowed three runs on eight hits and struck out five.
Ramos had a two-run single in Washington's big inning and Span doubled home two more. Ramos also had an RBI base hit in the third and has driven in eight runs over his last two games.
Andrew Cashner (5-4) had given up just 11 earned runs in his previous five outings, but surrendered six in two-plus frames on Friday. It was Cashner's first loss since May 30.