Question

Describe the basic characters of the oxide of third period elements across the period from left to right

Answer 1

In general, the electropositive character of the oxide's central atom will determne whether the oxide will be acidic or basic. The more electropositive the central atom the more basic the oxide. The more electronegative the central atom, the more acidic the oxide. Electropositive character increases from right to left across the periodic table and increases down the column.

A resultant borderline between basic and acidic oxides occurs along a diagonal.

Properties of s- and p-Block Elements

Li Be B C N O F

Na Mg Al Si P S Cl

K Ca Ga Ge As Se Br

Rb Sr In Sn Sb Te I

Cs Ba Tl Pb Bi Po At

Basic Oxides

Amphoteric Oxides

Acidic Oxides

There are three nonmetal oxides from the upper right portion of the periodic table, CO, NO, and N2O, which have such low oxidation numbers for the central atom that they give neutral aqueous solutions.

Since the acidity of a cation rises rapidly with charge, d-block elements which exhibit a wide variety of oxidation numbers may have one or more oxides that exhibit only basic properties and one or more oxides that exhibit only acidic properties. The higher the oxidation number the more acidic the corresponding oxide. Chromium is an example of such an element.

Oxide Oxidation Number Category

CrO Cr2+ basic

Cr2O3 Cr3+ amphoteric

CrO3 Cr6+ acidic