Thank you JohnBS this surpisingly helped me install ver 6.1. I wonder how many people will be getting around with a periodic tables app. What worked for me:
Code posted by Bernie
here Ran the code got some errors about Qt. Found this thread. Installed Kalzium from raspian add/remove software. Re-ran code without uninstalling the first failed install. Second install appears to be working well. This is on a Raspberry Pi 400 with Raspian desktop 64-bit