Final answer:
The term scandium III oxide denotes a compound with scandium in a +3 oxidation state, losing three electrons from its valence shell. The correct formula for scandium III oxide is Sc2O3. The Roman numeral III indicates this oxidation state, leading to the formula Sc2O3 after balancing the charges of scandium (+3) and oxygen (-2) using the crossover method.
Step-by-step explanation:
The name scandium III oxide refers to a compound consisting of scandium ions with a +3 oxidation state and oxide ions.
Scandium, when it forms ions, loses three electrons from its valence shell, which includes two 4s electrons and one 3d electron, resulting in a Sc3+ ion.
In this context, the Roman numeral III indicates that scandium has lost three electrons and thus carries a 3+ charge. Oxygen, in most cases, gains two electrons to form an oxide ion with a 2- charge.
When combining scandium and oxygen to form scandium III oxide, the charges must balance, resulting in the chemical formula Sc2O3.
Here, two scandium ions, each with a +3 charge, balance the three oxide ions with a 2- charge, as reflected by the respective subscripts in the chemical formula.
To derive the formula for scandium III oxide from the charges, we use the crossover method where the charge on scandium becomes the subscript for oxygen, and the charge on oxygen becomes the subscript for scandium.
This results in the correct formula of Sc2O3.