When methane (CH₄) is burnt in air, it undergoes a combustion reaction with oxygen (O₂) in the air, producing carbon dioxide (CO₂), water (H₂O), and heat energy.

Here's the balanced chemical equation for the reaction:

CH₄ + 2O₂ → CO₂ + 2H₂O + Heat

Here's what happens step-by-step:

1. Methane and Oxygen React: Methane molecules (CH₄) react with oxygen molecules (O₂) in the air.

2. Breaking and Forming Bonds: The bonds within the methane and oxygen molecules break, and new bonds form to create carbon dioxide (CO₂) and water (H₂O) molecules.

3. Energy Release: This process releases a significant amount of energy, which is why methane burning is used as a fuel source. The heat produced is what makes the flame visible.

In summary:

* Reactants: Methane (CH₄) and Oxygen (O₂)

* Products: Carbon dioxide (CO₂), water (H₂O), and heat energy

* Energy Change: Exothermic reaction (releases energy)

Important Note: The burning of methane is a major contributor to greenhouse gas emissions, as carbon dioxide is a potent greenhouse gas.