The Foundations of Chemistry

Metal Oxide
Water 88n Metal Hydroxide (base)

sodium oxide Na 2 O(s) H 2 O(
)88n2 NaOH(aq) sodium hydroxide

calcium oxide CaO(s) H 2 O(
)88nCa(OH) 2 (aq) calcium hydroxide

barium oxide BaO(s) H 2 O(
)88nBa(OH) 2 (aq) barium hydroxide

Recall that oxidation states are
indicated by red numbers in red
circles.

258 CHAPTER 6: Chemical Periodicity

 2

 4

 3

Carbon burns brilliantly in pure O 2
to form CO 2.

The oxides of the Group IA metals and the heavier Group IIA metals dissolve in water

to give solutions of strong bases. Most other metal oxides are relatively insoluble in water.

Reactions of O 2 with Nonmetals

Oxygen combines with many nonmetals to form molecular oxides.For example, carbon burns

in oxygen to form carbon monoxide or carbon dioxide, depending on the relative amounts

of carbon and oxygen.

2C(s)O 2 (g)88n2CO(s) (excess C and limited O 2 )

C(s)O 2 (g)88nCO 2 (g) (limited C and excess O 2 )

Carbon monoxide is a very poisonous gas because it forms a stronger bond with the

iron atom in hemoglobin than does an oxygen molecule. Attachment of the CO molecule

to the iron atom destroys the ability of hemoglobin to pick up oxygen in the lungs and

carry it to the brain and muscle tissue. Carbon monoxide poisoning is particularly insid-

ious because the gas has no odor and because the victim first becomes drowsy.

Unlike carbon monoxide, carbon dioxide is not toxic. It is one of the products of the

respiratory process. It is used to make carbonated beverages, which are mostly saturated

solutions of carbon dioxide in water; a small amount of the carbon dioxide combines with

the water to form carbonic acid (H 2 CO 3 ), a very weak acid.

Phosphorus reacts with a limited amount of oxygen to form tetraphosphorus hexoxide,

P 4 O 6 :

P 4 (s)3O 2 (g)88nP 4 O 6 (s) tetraphosphorus hexoxide