Question

Predict the physical properties and relative reactivity of Rb, Cs, and Fr

(From the periodic table)

Answer 1

You would expect the reactive to go up as you go down the table because that last outside electron is further and further away from the nucleus. Reactivity should be Li<Na<K<Rb<Cs<Fr.

Look at the melting points for
Li about 180
Na about 98
K about 63
You can see about how much the m.p. decreases as you go down the table. You might guess Rb at 40 or so and Cs and Fr less than that.

Boiling points. Again, look up the b.p. of Li, Na, and K see if there is a trend, then apply that to Rb, Cs and Fr.