Polarizability

[AlyssaBei_1F]

Can someone explain to me how to determine which atom has a higher polarizability?

[Cody Do 2F]

An atom is highly polarizable if it readily undergoes a large distortion (in layman's terms, if the atom's electron cloud is easily distorted). An atom can be expected to be highly polarizable if it's large as the outer electrons are not as strongly attracted to the positive nucleus and thus not held as tightly.

On the other hand, an atom has high polarizing power if it causes large distortions. Atoms that are small and highly charged are expected to have high polarizing power because their small size means that their positive nucleus can get very close to another atom and thus affect the electron cloud.

[AlyssaBei_1F]

Is there a trend for polarizability?

[Cody Do 2F]

Since polarizability depends on the size of the atom (large atoms = highly polarizable), its trend would follow that of atomic radius. Thus, an atom's size (and it's polarizability) increases as you go down a group and decreases as you go from left to right on a period.