def atomic_masses() -> dict:
    """
    Function which returns the atomic and molecular masses.

    Returns
    -------
    dict
        Dictionary with the atomic and molecular masses.
    """

    masses = {}

    # Atoms
    masses["H"] = 1.0
    masses["He"] = 4.0
    masses["C"] = 12.0
    masses["N"] = 14.0
    masses["O"] = 16.0
    masses["Na"] = 23.0
    masses["Na_lor_cur"] = 23.0
    masses["Na_allard"] = 23.0
    masses["Na_burrows"] = 23.0
    masses["Mg"] = 24.3
    masses["Al"] = 27.0
    masses["Si"] = 28.0
    masses["P"] = 31.0
    masses["S"] = 32.0
    masses["Cl"] = 35.45
    masses["K"] = 39.1
    masses["K_lor_cut"] = 39.1
    masses["K_allard"] = 39.1
    masses["K_burrows"] = 39.1
    masses["Ca"] = 40.0
    masses["Ti"] = 47.9
    masses["V"] = 51.0
    masses["Fe"] = 55.8
    masses["Ni"] = 58.7

    # Molecules
    masses["H2"] = 2.0
    masses["H2O"] = 18.0
    masses["H2O_HITEMP"] = 18.0
    masses["H2O_main_iso"] = 18.0
    masses["CH4"] = 16.0
    masses["CH4_main_iso"] = 16.0
    masses["CO2"] = 44.0
    masses["CO2_main_iso"] = 44.0
    masses["CO"] = 28.0
    masses["CO_all_iso"] = 28.0
    masses["CO_all_iso_Chubb"] = 28.0
    masses["CO_all_iso_HITEMP"] = 28.0
    masses["NH3"] = 17.0
    masses["NH3_main_iso"] = 17.0
    masses["HCN"] = 27.0
    masses["C2H2,acetylene"] = 26.0
    masses["PH3"] = 34.0
    masses["PH3_main_iso"] = 34.0
    masses["H2S"] = 34.0
    masses["H2S_main_iso"] = 34.0
    masses["VO"] = 67.0
    masses["VO_Plez"] = 67.0
    masses["TiO"] = 64.0
    masses["TiO_all_Exomol"] = 64.0
    masses["TiO_all_Plez"] = 64.0
    masses["FeH"] = 57.0
    masses["FeH_main_iso"] = 57.0
    masses["OH"] = 17.0

    return masses