You can do both! by: David from https://www.piano-play-it.com
Hi Aya,
The staright answer to your question is that chords are supposed to be played as a group of atleast three notes.
So I'd play the notes at the same time.... Please view our our Piano Chords Section where you can learn more about this issue.
However, chords can be played in different ways and one way is to play them as Arpeggios, which is a way to break a chord in a nice sequence by just playing one note or a few notes in a time.
I hope I gave you a satisfying answer. Don't hesitate to bring up more questions...