* Extremely low temperature: Hydrogen needs to be cooled down to a temperature below its freezing point, which is -259.16 °C (-434.49 °F), or 14.01 K.
* High pressure: At normal atmospheric pressure, hydrogen remains a gas even at its freezing point. You need to apply significant pressure to force the hydrogen molecules to solidify.
Types of solid hydrogen:
* Solid molecular hydrogen (H2): This is the most common form of solid hydrogen. It's formed under moderate pressure and is a clear, crystalline solid.
* Solid metallic hydrogen (H): This exotic form of hydrogen is created under extremely high pressure (millions of times atmospheric pressure). It's predicted to be a superconductor and a potential fuel source with high energy density.
Why is solid hydrogen rare?
Hydrogen is the lightest element, and its atoms have weak intermolecular forces. This means it takes very low temperatures and high pressure to overcome these forces and force the hydrogen atoms to become a solid.
Interesting fact: Solid hydrogen is used in research, particularly in the field of nuclear fusion. It's also used in some types of rocket fuel.
