Pulling any information from a dictionary with a user input

[buran]

It's just about accessing dictionary data. You may need to loop (one way or another) over the dict to find all elements that satisfy certain criteria. below are some examples, but it's not exhaustive list of approaches.

 assuming dict is named periodic_table (I will come to this a bit later)

# using for loop
for element in periodic_table.values():
    if element['Type'].endswith('Metal'):
        print(element)

# using list comprehension
radioactive_elements = [element['name'] for element in periodic_table.values() if element['Radioactive']]
print(radioactive_elements)

# using built-in function filter
for element in filter((lambda x: x['Type'] == 'Nonmetal'), periodic_table.values()):
    print('{name} : {Mass}'.format(**element))

you create your dict in a very naive, although perfectly valid way.
Instead of creating empty dict and assign key, value pairs, you can simply create dict like this

periodic_table = {'H':{'name': 'Hydrogen', 'number': 1, 'Mass': 1.008, 'Type': 'Nonmetal', 'Radioactive': False},
'He': {'name': 'Helium', 'number': 2, 'Mass': 4.003, 'Type': 'Noble Gas', 'Radioactive': False},
.... here go rest of the elements ....
}

I would make all keys either lower case or first char upper case. at the moment some of the keys are lowercase , e.g. 'name' and some have first char upper case, e.g. 'Mass'. I will choose one or the other and stick to it.
iFunKtion already mentioned database and this is fine, but at least I would consider to put the periodic table data in external file, e.g. json (see attached).

the access it like this

import json
with open('mendeleev.json', 'r') as f:
    periodic_table = json.load(f)

Finally, if you plan to work with periodic table in long run, you don't need to invent the wheel - there are several packaged that have implemented the periodic table of elements and provide nice functionality to work with the table. have a look at some of them:

https://pypi.python.org/pypi?%3Aaction=s...odic+table