Module 4.2 Common Reaction Types |
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Combination ReactionsA combination reaction is a reaction in which two reactants combine to form one product. Oxygen and the halogens are very reactive elements and are likely to undergo combination reactions with other elements. When a metal undergos a combination reaction with oxygen, a metal oxide is formed (similarily, a metal halide is formed if reacted with one of the halogens). You see the products of this type of reaction whenever you see rust. Rust is the product of a combination reaction of iron and oxygen: Aluminum also reacts with oxygen to form aluminum oxide. What is the molecular formula for aluminum oxide? |
The oxygen ion will have a charge of -2 and the aluminum ion will have a charge of +3. How can these two ions combine to form a neutral compound? |
While the compound you have suggested is electrically neutral, it is not the simplest way aluminum and oxygen can combine. |
Good! Oxygen and the halogens can also undergo combination reactions with non-metals resulting in molecular compounds. An example of this is the reaction occuring in the fuel cells that power space shuttles: The molecular formula for these are more difficult to predict and are not discussed here. |