single positional indexer is out-of-bounds while using chemlib with an input

Question

I'm trying to make a chemistry dictionnary were a user can get infos just by asking.

here is the code:

Input = input("enter element symbol")
User_element= Element(Input)
ElementPropreties = User_element.properties

User_Info = input("what do you want ?")
if User_Info == 'properties':
    print(ElementPropreties)
else:
    print("Thank you for your visit user" + str(r1))
if User_Info == 'Valence':
  print(User_element.Valence)

def Dalton_law_function():
  if User_element.Density == User_element.Density:
    print("The law of multiple proportions from Dalton is repected for this mix")
  if  User_element.Density != Element.Density:
    print("The law of multiple proportions from Dalton doesnt respect for this mix") 

def User_info_mp():
  if User_Info == "multiple proportions":
    return Dalton_law_function()


User_info_mp()

here is the mistake I've got when I've run it:

IndexError                                Traceback (most recent call last)
<ipython-input-37-d19852e411ef> in <module>()
   
    
    IndexError: single positional indexer is out-of-bounds