Hopefully not. Don't use merge and center. It only leads to trouble with selecting, sorting and referencing. Use Center across selection instead. It's in the Alignment tab of the Formatting dialog.
And, by the way, each command in the ribbon can be accessed with a shortcut. Hit the alt key, then the letter for the ribbon you want to open, then the letter for the command you want to use. In the case of Merge and center, this would be
Alt - H - M - C
But don't use it, please.