6.3.2 Trends in Boiling Points

• If you were to compare the boiling points of helium and radon, what trend would you expect to see?

  Radon has a higher boiling point than helium
• What are noble gases known for?

  They are very unreactive elements
• What does it mean for noble gases to be monatomic?

  They consist of single atoms, not molecules
• Which noble gas has the highest boiling point and why?

  Rn, due to largest size and most electrons
• What is the relationship between atomic radius and ionization energy?

  • As atomic radius increases, ionization energy decreases
  • Larger atoms have lower ionization energies
• What happens to the movement of noble gas atoms as their boiling points increase?

  They become harder to move from gas to liquid
• How does the stability of noble gases contribute to their applications in technology?

  Stability allows safe use in lights and lasers
• What type of forces do noble gases experience?

  London forces
• What does the increase in boiling points down Group 0 indicate?

  It indicates the properties of noble gases.
• What does a stable electron configuration mean for noble gases?

  Their outer electron shells are full
• What are the trends in melting and boiling points of the noble gases as atomic number increases?

  • Melting and boiling points generally increase with increasing atomic number
  • Helium has the lowest melting and boiling points
  • Xenon has the highest melting and boiling points
• If you were given a sample of an unknown noble gas, how could you use the information in this graph to identify it?

  • Measure the melting and boiling points of the unknown gas
  • Compare the measured values to the data in the graph
  • The noble gas with matching melting and boiling points is the identity of the unknown sample
• What factors contribute to the increase in boiling points of noble gases?

  • Increase in atomic number
  • Increase in atomic mass
  • Increase in atomic size
  • Greater difficulty in transitioning from gas to liquid
• What happens to interatomic attractions as atomic radius increases in Group 0 elements?

  Interatomic attractions become stronger
• How does the size of noble gas atoms affect their boiling points?

  Larger atoms are harder to move from gas to liquid
• What is the melting point of helium (He)?

  $0.95\text{ K}$
• What is the relationship between atomic radius and boiling point in Group 0 elements?

  • Atomic radius increases from He to Rn
  • Larger atomic radius leads to stronger interatomic attractions
  • Stronger attractions result in higher boiling points
• What factors influence the boiling points of noble gases?

  • Atomic Size: Larger size leads to stronger London forces and higher boiling point.
  • Electron Number: More electrons result in stronger London forces.
• What is the boiling point of krypton (Kr)?

  $119.93\text{ K}$
• What is the melting point of argon (Ar)?

  $83.81\text{ K}$
• How do the boiling points of the noble gases change as you go down the periodic table?

  • The boiling points increase as the atomic number and atomic mass increase.
  • This is due to the increasing van der Waals forces between the larger, more polarizable atoms.
• What is the boiling point of neon (Ne)?

  $27.07\text{ K}$
• How does electron affinity relate to the periodic table?

  • Electron affinity generally increases from left to right across a period
  • Electron affinity generally decreases from top to bottom in a group
• What visual representation is used to indicate atomic radius in the study material?

  Teal arrows
• How do argon, krypton, and xenon compare to helium and neon regarding liquefaction?

  They liquefy easier than helium or neon.
• What states are argon, krypton, and xenon at room temperature?

  They are gases.
• Why do boiling points of noble gases increase as we move down the group?

  Due to increasing mass and size of atoms
• Which element has the largest atomic radius in Group 0?

  Radon (Rn)
• Why are helium and neon gases at room temperature?

  Because their boiling points are low.
• Why is radon a liquid at room temperature?

  Due to its high boiling point.
• What is the boiling point of helium (He)?

  -269 °C
• What are the limitations of using only melting and boiling point data to identify noble gases?

  • Some noble gases have very similar melting and boiling points (e.g. argon and krypton)
  • Additional information like density or spectroscopic data would be needed to definitively identify the gas
  • The graph only shows data for the 6 stable noble gases, so it cannot identify radioactive noble gases
• Why do larger atoms have stronger London forces?

  Their larger electron clouds can become better polarized
• What state are helium and neon at room temperature?

  They are gases.
• What does it mean for noble gases to be inert?

  They do not readily react with other elements
• What is the relationship between atomic number and boiling point in noble gases?

  Higher atomic number correlates with higher boiling point
• What are the boiling points of the noble gases shown in the image?

  • Helium (He): -269 °C
  • Neon (Ne): -246 °C
  • Argon (Ar): -186 °C
  • Krypton (Kr): -153 °C
  • Xenon (Xe): -108 °C
  • Radon (Rn): -62 °C
• Why are noble gases often used in lights or lasers?

  Because of their stability
• What is the boiling point of argon (Ar)?

  -186 °C
• What type of intermolecular forces are stronger in larger atoms?

  London forces