Put these elements in order of decreasing electronegativity, with the highest electronegative element as number 1.
a. tin (Sn, Group 14, Period 5)
b. rubidium (Rb, Group 1, Period 5)
c. bromine (Br, Group 17, Period 4)
d. lithium (Li, Group 1, Period 2)
e. cadmium (Cd, Group 12, Period 5)