As Bryan says, you're probably not using the Python version you think you're using. PyCharm tends to install its own version of Python. Once you have more than one version of Python installed, things get trickier.
To see what's happening, try running this script:
import sys
print(sys.executable, sys.version)
Or run those similar commands from the command line. That should help clarify matters.
The sys.executable
will show you the full path to your Python executable. Great for seeing where the used Python installation is located.
I don't use Python on Linux, but perhaps one of your Python installations is version 2, in which case you would need to use:
from Tkinter import *
which is another way to confirm that the Python is version 2 rather than 3. If this is the case, you'll want to move to Python 3. I don't think anyone writes new projects in Python 2 anymore. It's defunct, purely legacy.
It's also possible that Python is installed on Linux without Tkinter. There are other posts on how to install Tkinter on Linux. For instance, you can check out ImportError: No module named 'Tkinter'