Final answer:
The gas giants—Jupiter and Saturn—have metallic hydrogen in their interiors due to high internal pressures, which Uranus and Neptune, the ice giants, lack due to lower pressures.
Step-by-step explanation:
The gas giants have a characteristic component in their interiors known as metallic hydrogen. The immense pressures within gas giants like Jupiter and Saturn are sufficient to convert molecular hydrogen into metallic hydrogen, a state in which hydrogen behaves like an electrical conductor. Uranus and Neptune, sometimes referred to as ice giants, do not reach the necessary internal pressures to form metallic hydrogen in their interiors. The atmospheres of all the giant planets are dominated by hydrogen, leading to a chemistry that is largely hydrogen-based, with compounds such as methane (CH4) and ammonia (NH3) being prevalent.