Which Has a Higher Boiling Point: He or Ar?

When comparing the boiling points of two elements, it’s essential to consider various factors such as atomic structure, intermolecular forces, and molecular weight. In this article, we will delve into the comparison between helium (He) and argon (Ar) to determine which one has a higher boiling point. Let’s explore the details.

Atomic Structure

Helium and argon are both noble gases, located in Group 18 of the periodic table. Helium has an atomic number of 2, while argon has an atomic number of 18. Despite their similar electronic configurations, their atomic structures play a crucial role in determining their boiling points.

Helium has only two electrons, which are in the 1s orbital. This means that helium atoms have a very small atomic radius and a weak London dispersion force. On the other hand, argon has 18 electrons, with the outermost electrons in the 3p orbital. This larger atomic radius and more extensive electron cloud result in stronger London dispersion forces between argon atoms.

Intermolecular Forces

Intermolecular forces are the attractive forces between molecules. In the case of noble gases, the primary intermolecular force is the London dispersion force, which arises from the temporary fluctuations in electron distribution. The strength of these forces depends on the size and shape of the atoms involved.

As mentioned earlier, helium atoms have a smaller atomic radius and weaker London dispersion forces compared to argon atoms. This means that helium molecules experience weaker intermolecular forces, resulting in a lower boiling point. Conversely, argon molecules have stronger intermolecular forces due to their larger atomic radius and more extensive electron cloud, leading to a higher boiling point.

Molecular Weight

Molecular weight is another crucial factor that influences the boiling point of a substance. Generally, substances with higher molecular weights have higher boiling points. This is because heavier molecules have more electrons and a larger electron cloud, resulting in stronger intermolecular forces.

In the case of helium and argon, helium has a molecular weight of 4.0026 g/mol, while argon has a molecular weight of 39.948 g/mol. This significant difference in molecular weight further supports the idea that argon has a higher boiling point than helium.

Boiling Points

Based on the information discussed above, we can now determine the boiling points of helium and argon. The boiling point of helium is -268.9掳C (-452.0掳F), while the boiling point of argon is -186.0掳C (-302.8掳F). This clearly indicates that argon has a higher boiling point than helium.

Conclusion

In conclusion, when comparing helium and argon, we find that argon has a higher boiling point. This is due to its larger atomic radius, more extensive electron cloud, and stronger London dispersion forces. Additionally, the higher molecular weight of argon also contributes to its higher boiling point. Understanding the factors that influence boiling points can help us better comprehend the properties of different elements and their applications in various fields.