This is because copper is a transition metals.
Transition metals don't have a definite charge, you can see this on the periodic table. However, Alkali Earth, Alkali, Metalloids, Non-metals, Halogens, Noble Gases, etc, all have a specified charge.
Although, there are exceptions: Zinc, Gold, and Cadmium.
Aluminum is a poor metal, but it has it's own charge (3+).
Therefore, Copper has roman numerals due to the fact that it's a transition metal and Aluminum is a poor metal.
Hope this helps!
It affects the volume of air you can inhale.
<span>This is a 2 step dissociation reaction. But to find \(\large K_a = \frac{[prodcuts]}{[reactants]}\)</span>
