Create a dictionary of chemical elements and their symbols.
user
elements = {
    'Hydrogen': 'H',
    'Helium': 'He',
    'Lithium': 'Li', 
    'Berylium': 'Be',
    'Boron': 'B',
    'Carbon': 'C',
    'Nitrogen': 'N',
    'Oxygen': 'O',
    'Fluorine': 'F',
    'Neon': 'Ne',
    'Sodium': 'Na',
    'Magnesium': 'Mg',
    'Aluminum': 'Al',
    'Silicon': 'Si', 
    'Phosphorus': 'P',
    'Sulfur': 'S',
    'Chlorine': 'Cl',
    'Argon': 'Ar',
    'Potassium': 'K',
    'Calcium': 'Ca'
}
assistant