Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
The Noble Gases are located in Group 0 (or Group 18) of the Periodic Table. The group includes Helium (), Neon (), Argon (), Krypton (), Xenon (), and Radon ().
They are characterized by having a full valence shell of electrons. Helium has the configuration , while the others have a valence configuration of .
Due to their stable electronic arrangement, they are chemically inert (unreactive) and do not readily form compounds or ions under standard conditions.
Noble gases are monatomic, meaning they exist as individual atoms rather than molecules ( instead of ).
Physical trends: Boiling points and densities increase down the group. This is due to the increase in atomic mass and the strength of London dispersion forces (intermolecular forces) as the number of electrons increases.
Common uses include for weather balloons (low density/non-flammable), for an inert atmosphere in light bulbs, and for advertising signs.
📐Formulae
💡Examples
Problem 1:
Explain the trend in boiling points from Helium () to Xenon ().
Solution:
The boiling point increases down the group ().
Explanation:
As we move down Group 0, the number of electrons in the atoms increases. This lead to stronger temporary dipoles and thus stronger London dispersion forces between the monatomic atoms. More thermal energy is required to overcome these forces to change the state from liquid to gas.
Problem 2:
Why is Argon () used instead of air in incandescent light bulbs?
Solution:
Argon is chemically inert and does not react with the hot tungsten filament.
Explanation:
Air contains oxygen (), which would react with the tungsten filament at high temperatures, causing it to burn out (oxidation). Since has a full outer shell (), it provides a non-reactive environment that preserves the filament.
Problem 3:
Calculate the approximate density of Neon () at RTP (Room Temperature and Pressure), given its relative atomic mass is and molar volume is .
Solution:
Explanation:
The density is found by dividing the molar mass by the volume occupied by one mole of gas at RTP. Density increases as the atomic mass increases down the group.