4/8/2015 7:30AM I got this information from apple chat and if more questions I have case number.

I own a new mac mini and a new apple wireless keyboard. On the keyboard I don't think the F5 & F6 keys are used for anything. I was wondering if I could make the F5 key do something for me. For example to put the display to sleep I have to press 3 keys (shift, control, eject). Is it possible for me to just be able to press only the F5 key to do the same thing (put the display to sleep). If it is possible, how would I do this?

Your Case ID:

776720864

We may ask you for it during your chat session.

After the chat session, you can use this number to review your case.

How to change the behavior of function keys on your Mac

If your Apple keyboard has icons printed on some of the keys on its top row, these keys can be used to perform the special features shown in each icon. They can also be used as standard function keys (F1 through F12). The action performed by standard function keys varies depending on the app you're using, or depending on the keyboard shortcuts listed in the Keyboard & Mouse pane of System Preferences.

By default, pressing one of these keys performs the special feature indicated by the icon printed on the key. For example, pressing the keys with speaker icons adjusts the volume.  If you want to use one of these keys as a standard function key, hold the Fn key (usually in the lower left corner of the keyboard) while pressing the function key. Pressing Fn-F10 (speaker icon) performs the function assigned to the F10 key instead of toggling mute on or off.

If you prefer the top row of keys to always behave as standard function keys without holding the Fn key:

1. Choose System Preferences from the Apple menu.
2. From the View menu, choose Keyboard.
3. Click the Keyboard tab if it is not already selected
4. Enable "Use all F1, F2, etc. keys as standard function keys."

With this option enabled, the top row of keys acts as standard function keys (F1 - F12). To use a feature indicated by the icon printed on a key, hold Fn while pressing the key.

Now chatting with Aha, case # 776720864

AhaThanks for contacting AppleCare chat support. My name is Aha. Please give me a moment to look over your information.
Me:I own a new mac mini and a new apple wireless keyboard. On the keyboard I don't think the F5 & F6 keys are used for anything. I was wondering if I could make the F5 key do something for me. For example to put the display to sleep I have to press 3 keys (shift, control, eject). Is it possible for me to just be able to press only the F5 key to do the same thing (put the display to sleep). If it is possible, how would I do this?
AhaGreetings, Bob! Just in case you need to reference it, your case number is 7776720864.
Me:ok
AhaOkay. You called the right place, and I'm happy to provide that information.
AhaHey how's it going today Bob?
Me:just have the question I asked
AhaI’ve had that same thought too about those functions keys!
Sharing Article How to change the behavior of function keys on your Mac(Opens in new window):
AhaYou may have covered some of these steps already, so I just want to make sure you have it saved :) Glance over the article real quick and let me know if there are any steps you may not have covered yet. 
AhaHowever giving them other functions is not an option but sounds like a really cool feature to add in the future.
AhaWe always appreciate customers who take the time to give us their feedback.You can submit your own feedback about this at http://www.apple.com/feedback/(Opens in new window)(Opens in new window)(Opens in new window)(Opens in new window)(Opens in new window) . We have an entire team here at Apple, whose entire job is dedicated to reviewing this feedback, and escalating it to the proper outlets (such as the engineers for iTunes, iPhone, iPad, etc.), so you can rest assured that your voice will be heard! The more feedback we receive about product features, the more likely we are to implement them! With that said, I'm more than happy to walk you through submitting feedback today!
Me:I would like to read what you gave me later. If any problems i have the number of this chat.
Me:Thanks very much, I will copy and paste all this. Bye,
AhaGreat! I will provide you with a Case Number and I'll also send you a transcript of our chat so you can refer back if you need to it. If you would feel more comfortable, I could also schedule a callback from Apple to make sure we've got your issue resolved. How does that sound?
Me:No thanks. If problem I will use case number. Thanks bye
AhaYou are my number one priority, so I want to make sure everything is ok before you end the chat. Do you feel like we have come to a resolution by laying out the exact steps to take once you end this chat?
Me:You have given me what I want. Thanks.
AhaBob, it has been my pleasure to help you today! Do you feel that I have addressed all your questions, and that I have provided you with a path to a resolution, that meets your expectations?
Me:Yes thanks, bye
AhaBob, it was awesome chatting with you!  I will go ahead and end the chat from my side, but if you need anything else at all, we are here for you 24/7 in chat!  I hope you have a great rest of your day!