Sodium (Na) reacts vigorously with water (H₂O) to produce sodium hydroxide (NaOH), also known as lye, and hydrogen gas (H₂):

2 Na (s) + 2 H₂O (l) → 2 NaOH (aq) + H₂ (g)

Here's what happens:

* Sodium (Na) is a highly reactive metal.

* Water (H₂O) contains hydrogen and oxygen.

* When sodium comes into contact with water, it donates an electron to a hydrogen atom in water, forming sodium hydroxide (NaOH).

* The other hydrogen atom from water combines with another hydrogen atom to form hydrogen gas (H₂), which is released as bubbles.

Important Note: This reaction is highly exothermic, meaning it releases a lot of heat. The heat can cause the hydrogen gas to ignite, creating a fire or even an explosion. Therefore, it's crucial to handle sodium with extreme care and never mix it with water in large quantities.