Sites like Facebook and others with intensive graphics are ram hogs and crashing will occur at times. Do you close your apps completely regularly? All apps open are using some ram and closing them will free up this ram.
Also clearing your history and cookies occasionally will free up more ram - Settings - Safari - clear History and Cookies.
Do you also restart/reset your iPad occasionally.....it's a good idea to do these steps just to keep your iPad running well.
And in case you don't know, and I apologise if you do -
Closing apps - From the home screen do the four finger swipe up or double press the home button to reveal your multi task bar. These are all the apps that you have opened at one time. If you have updated to IOS7 - just swipe up on the image above the app icon to close it. If on an earlier OS - Long press the app until it jiggles and a red minus sign will appear above it. Press the minus sign, this will close the app, not delete it, now press the home button to return to your screen.
Restart - Press and hold the power off button, the one at the top right. You will see a slide appear to power off, slide this and the screen will go dark and a Whirly will appear. When the Whirly disappears your iPad is now off. Press the power button again until the Apple logo appears, this will take a few seconds and your iPad will restart.
Reset - Hold the power off button and the home button simultaneously, keep holding them in and you may see the power off slide appear and disappear, wait until you see the Apple logo appear before releasing the buttons. It will take a little longer for your iPad to start.