The statement that all materials, except helium (He), become solids when the temperature is sufficiently lowered is not entirely accurate. While it is true that most substances tend to solidify as their temperature decreases, there are exceptions to this rule.
The phase in which a material exists (solid, liquid, or gas) depends on the balance between intermolecular forces and thermal energy. When the temperature is high, thermal energy dominates, causing the particles to move more rapidly and overcome the intermolecular forces. This results in a substance being in the liquid or gaseous state. However, as the temperature decreases, the thermal energy decreases, and the intermolecular forces become more significant.
In most cases, the intermolecular forces, such as van der Waals forces or hydrogen bonding, are strong enough to bring the particles close together and form a solid lattice structure when the temperature is sufficiently lowered. This is why many substances, including water, metals, salts, and various organic compounds, solidify at lower temperatures.
Helium, on the other hand, is an exception due to its unique properties. It remains a gas even at extremely low temperatures, including close to absolute zero. This is because helium atoms are very light and have weak interatomic forces. The attractive forces between helium atoms are relatively weak, and the kinetic energy associated with their motion is sufficient to prevent them from forming a solid lattice.
It's important to note that there are other exceptional cases where materials can exhibit different phases at low temperatures, such as certain types of liquid crystals, superfluids, and Bose-Einstein condensates. These materials have distinct properties and behaviors that go beyond the simple solid-liquid-gas paradigm.