Acidic, basic, or amphoteric? [ENDORSED]

[Kristina Nguyen 1C]

How to tell the difference between them?

[Chem_Mod]

Students have been asking this question typically in reference to problem 12.17 where you are asked to identify whether a particular oxide is basic, acidic, or amphoteric.

In general, remember that if a compound does not have an obvious acidic hydrogen H (such as the case of weak acid acetic acid CH₃COOH, where the last H is lost or "deprotonated" during an acid/base reaction) or an obvious OH group that will be lost (such as the case of strong base NaOH) then the Lewis definition can be useful to predict whether a molecule will behave as an acid or base. Lewis acids accept and Lewis bases donate electron pairs (lone pairs). So it is best to draw the Lewis structure to evaluate this.

In the case of oxides, metals form basic oxides, nonmetals form acidic oxides, and the elements on the diagonal line formed by beryllium to polonium along with several d-block metals form amphoteric (they act both as acids or bases depending on the environment) oxides.

[elliekauffman1I]

Where exactly is the line that separates metals from nonmetals? And which elements from the d-block elements form amphoteric molecules?

[Rebecca Cheung 1E]

"Where exactly is the line that separates metals from nonmetals?" Not sure what answer you're exactly looking for but in speaking in terms of properties, metals are conductive, malleable, and solid (at room temp) and non-metals are not conductive, brittle, and gaseous/liquid/solid (at room temp). Heres also a colored periodic table to separate what is a metal and not a metal https://www.angelo.edu/faculty/kboudrea ... s_fig1.gif

[Cam Bear 2F]

If amphoteric oxides act both as acids or bases, what is the difference between amphiprotic and amphoteric oxides?