Is there an IDE that is recommended by the elementary OS developers?
Scratch + Terminal + Developer Libraries
Yep that's the set of software which are the official elementary SDK, as you can find out here.
Scratch is better than notepad (that's included with Windows), but is still a newcomer. You can later give these text editors a try:
All run in elementary. All are Open Source except Sublime Text but you can run an evaluation version and then purchase a license if you want.
Also the Github's Atom is based on Web Technologies and is the most customizable and heaviest of all four.