The reaction is as follows:

2Ca + O₂ → 2CaO

Here's a breakdown:

* Calcium (Ca) is a reactive metal.

* Oxygen (O₂) is a diatomic gas.

* Calcium oxide (CaO) is a white solid that is highly alkaline.

Calcium oxide is a very important industrial chemical, used in many applications, including:

* Cement production: It's a key ingredient in the making of cement, which is used in construction.

* Steelmaking: It's used to remove impurities from steel.

* Water treatment: It's used to adjust the pH of water.

* Agriculture: It's used to improve soil fertility.

Let me know if you have any other chemistry questions!