Here's why:

* Elements are the simplest pure substances that cannot be broken down into simpler substances by chemical means. They are the building blocks of everything around us.

Let's break down each element:

* Oxygen (O): A colorless, odorless gas that is essential for respiration and combustion.

* Carbon (C): A nonmetal that is the basis of all organic life and is found in many other compounds.

* Hydrogen (H): The lightest and most abundant element in the universe, and a key component of water.

* Sodium (Na): A soft, silvery-white metal that is highly reactive and is found in table salt.

While these elements have different properties and uses, they all share the commonality of being fundamental building blocks of matter.