Textbook Question 6A.17

[Keon Amirazodi 3H]

State whether the following oxides are acidic, basic, or
amphoteric: (a) BaO; (b) SO3; (c) As2O3; (d) Bi2O3.

3 questions:

1. How can we tell whether oxides are acidic, basic, or amphoteric? Is it true that metal oxides are generally basic, nonmetal oxides are generally acidic, and metalloid oxides are generally amphoteric?

2. If that trend is true, then why? Is it related to the electronegativity of the central atom?

3. If the trend is true, Bi is technically classified as a metal so why is it listed as amphoteric?

[Thomas Vu 1A]

Well you basically answered your first question, but thre reasoning to why could best be described by drawing the compounds out in water. SO3 which is a nonmetal oxide combines with h20 to form H2SO4 which is an acid, while BaO, a metal oxide, will have an O2- attract the H+ off of an H20 creating OH thus making the solution basic. Idk about the reasoning behind amphoteric but Bi is pretty close to the metalloid line which may describe its amphoteric quality

[Yichen Fan 3A]

Metal oxides contain ionic bonds so they will split into ions in water BaO into Ba2+ and O2-, and that O2- causes water to be basic. Nonmetal oxides mostly stays in water as a single molecule, you don't see SO3 splits into S6+ and O2-, and SO3 can accept more electrons, therefore it makes an acid.

[Chloe Little 3K]

Metalloid oxides are generally amphoteric but this doesn't mean that all amphoteric compounds are metalloid oxides. Bi2O3 is an amphoteric compound because it has both basic and acidic characters.