Describe the general trends in the following properties of the elements in Groups $13$ and $14$.
$(A)$ Atomic size
$(B)$ Ionization enthalpy
$(C)$ Metallic character
$(D)$ Oxidation states
$(E)$ Nature of halides

(N/A) For Group $13$:
$(A)$ Atomic size: Atomic radius generally increases down the group due to the addition of new shells. However,$Ga$ has a smaller atomic radius than $Al$ due to poor shielding by $d$-electrons.
$(B)$ Ionization enthalpy: The trend is irregular $(B > Al < Ga > In < Tl)$ due to the shielding effect of $d$ and $f$ orbitals and the increase in nuclear charge.
$(C)$ Metallic character: Increases down the group as ionization energy decreases.
$(D)$ Oxidation states: Group $13$ shows $+3$ and $+1$ (due to inert pair effect). Group $14$ shows $+4$ and $+2$.
$(E)$ Nature of halides: Group $13$ forms $MX_3$ type halides. Group $14$ forms $MX_2$ and $MX_4$ type halides.