def choose_most_elec_neg_potential(elem_lst, potential_dict):
    """Return the potential of the most electronegative element in a list of elements"""
    # if the element list is empty, return None
    if not elem_lst:
        return None
    # if the structure only contains 1 element, return None
    if len(potential_dict) == 1:
        return None
    # since the elements are already ranked by decreasing electronegativity
    # the first element in the list is by default the most electronegative one
    return potential_dict[elem_lst[0]]