The Germany international saw his spot-kick saved by Steve Mandanda eight minutes before half-time but went on to provide the assist for Jack Wilshere's second goal.
We have to enjoy it because we have 12 points now and [progress] is dependent on usMikel Arteta
Arteta, who missed a last-minute penalty against Fulham last season, says his team-mate will move on quickly.
"Penalties are very decisive moments," he said. "Only a detail makes it go in or out. I don't think it's about confidence.
"We start thinking about Saturday now and we have time to prepare for the game in Napoli. But we have to enjoy it because we have 12 points now and [progress] is dependent on us.
"Cardiff will be very tough. That’s why we need to get back and prepare well for Saturday to make sure we get the points again."Copyright 2017 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source