How can I add Tooltips to my mod(1.12.2)

[Mineco1006]

Hey I currently try to make a new Mod that is similar to the Minechem Mod. I want to add Tooltips and the atomic number of the elements on the left upper corner of the Item. Thanks for helping me!

[That_Martin_Guy]

Override the items addInformation method in the class of your item and add the tooltips you want in the string list that gets passed in as an argument.