Active metals react with hydrogen to form corresponding _______
Answers
Active Metal Reactions with Oxygen
The method used to predict the products of reactions of the main group metals is simple, yet remarkably powerful. Exceptions to its predictions arise, however, when very active metals react with oxygen, which is one of the most reactive nonmetals.
Lithium is well behaved. It reacts with O2 to form an oxide that contains the O2- ion.
4 Li(s) + O2(g)  2 Li2O(s)
Sodium, however, reacts with O2 under normal conditions to form a compound that contains twice as much oxygen.
2 Na(s) + O2(g)  Na2O2(s)
Compounds such as Na2O2 that are unusually rich in oxygen are called peroxides. The prefix per- means "above normal" or "excessive." Na2O2 is a peroxide because it contains more than the usual amount of oxygen. Peroxides contain the O22- ion.
The formation of sodium peroxide can be explained by assuming that sodium is so reactive that the metal is consumed before each O2 molecule can combine with enough sodium to form Na2O. This explanation is supported by the fact that sodium reacts with O2 in the presence of a large excess of the metal  or a limited amount of O2  to form the oxide expected when this reaction goes to completion.
4 Na(s) + O2(g)  2 Na2O(s)
It is also consistent with the fact that the very active alkali metals  potassium, rubidium, and cesium  react so rapidly with oxygen they form superoxides, in which the alkali metal reacts with O2 in a 1:1 mole ratio.
K(s) + O2(g)  KO2(s)
Potassium superoxide forms on the surface of potassium metal, even when the metal is stored under an inert solvent. As a result, old pieces of potassium metal are potentially dangerous. When someone tries to cut the metal, the pressure of the knife pushing down on the area where the superoxide touches the metal can induce the following reaction.
KO2(s) + K(s)  K2O(s)
Because potassium oxide is more stable than potassium superoxide, this reaction gives off enough energy to boil potassium metal off the surface, which reacts explosively with the oxygen and water vapor in the atmosphere.
Answer:
metal hydride is the answer