Here's why:

* It's a gas: Hydrogen exists as a gas at room temperature and pressure. Gases are generally transparent.

* It's colorless: Hydrogen gas itself has no color.

However, you can detect hydrogen in a few ways:

* Burning: When hydrogen burns, it produces a pale blue flame.

* Reactions: Hydrogen reacts with certain metals to produce visible products, like the popping sound and bubbles when it reacts with sodium.

* Special instruments: Spectrometers can detect hydrogen by its unique spectral signature.

So, while you can't see hydrogen directly, you can infer its presence through its chemical properties and interactions.