Temperature is indeed a measure of molecular agitation or the average kinetic energy of the molecules in a substance. However, it's important to understand that different substances have different molecular interactions and characteristics, which can affect their states at a given temperature.
In the case of solid iron at a higher temperature (1,000°C) compared to oxygen gas at a lower temperature (-10°C), it might seem counterintuitive based on the idea that gases have more energy and molecular agitation. However, this apparent contradiction can be explained by considering the specific properties of the substances involved.
Iron is a metal with strong metallic bonds between its atoms. These bonds are relatively strong, requiring a significant amount of energy to break and transition into a liquid or gas state. As a result, solid iron can exist at much higher temperatures compared to many other substances.
Oxygen, on the other hand, is a diatomic gas (O2) composed of oxygen molecules. The intermolecular forces holding oxygen molecules together are weaker than the metallic bonds in iron. Oxygen molecules can more easily separate and move freely, allowing them to exist as a gas at lower temperatures.
While gases generally have higher molecular agitation due to their greater freedom of movement, the state of a substance at a specific temperature depends on various factors, including the strength of intermolecular forces and the energy required to break or overcome those forces. Different substances exhibit different phase transition temperatures based on their unique molecular structures and interactions.
In summary, the state of matter at a given temperature is influenced not only by the average kinetic energy or molecular agitation but also by the specific molecular interactions and characteristics of the substance. This leads to variations in the phase transitions and the temperature ranges at which different substances exist in different states.