Hi
Google for privacy reasons have stopped passing the keyword for organic search. There are some ways around this and MOZ have done a White board Friday on it: http://moz.com/blog/100-percent-keyword-not-provided-whiteboard-tuesday
If you have Google Webmaster tools you can see the clicks and impressions for keywords in that. You can also use landing pages report in Google Analytics (with an organic search segment) to give a clue to the keywords used.
Hope that helps and let me know if you need more?