Why do magnesium and oxygen combine?

Becuse magnesium is a earth alkaline metal and oxygen is a nonmetal(read explanation)

Explanation:

Magnesium has 2 valence electrons where oxygen has 6 valence electrons. Magnesium has tendency to give electrons to oxygen and oxygen has tendency to gain electrons. They are both trying to complete their last shell to 8 which is called the octet rule. Because they both want to complete each other because of the reasons that I told they combine to be stanle atoms like noble gases.

- "the choice that is not an indicator of a chemical change is "state of matter changes". more common than not, chemical reactions produce energy in the form of light or heat. along with energy, they also produce a new substance called the product that could be in any state of matter (solid, gas, or liquid)."

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