The periodic table highlighting the noble gases – they occupy the group furthest to the right
- Although chemically inert, the noble gases do have several applications and uses
- Helium is used for filling balloons and weather balloons as it is less dense than air and does not burn
- Neon, argon, and xenon are used in advertising signs
- Argon is used to provide an inert atmosphere for welding
- Argon is also used to fill light bulbs, as like the other noble gases, it has the unusual property of glowing brightly when a high potential difference is applied to the gas under low pressure
- As with other groups, there are trends in the physical properties of the noble gases
- The noble gases have very low melting and boiling points
- They show an increase in boiling point as we move down the group due to an increase in the relative atomic mass (the atoms get larger as you move down the group)
- This leads to an increase in intermolecular forces between atoms, increasing the amount of energy needed to overcome these forces to change state
- Elements further down the group have higher boiling points but these still lie below 0 ºC.
- Helium has the lowest boiling point of all known elements at -269 ºC, while radon boils at around -60 ºC.
This graph shows the trend in boiling point of the noble gases
- Since the group 0 elements are all gases at room temperature, individual atoms are widely spaced apart, giving them low densities
- Their density increases as you move down the group
- Elements further down the group would be expected to have higher densities
- Helium is the lightest noble gas and radon is the heaviest
This graph shows the trend in the densities of the noble gases
Exam questions often give you the boiling point of a noble gas and ask you to estimate the value of another one, so it is important to remember the general trends in the group 0 elements. You do not need to learn these values exactly!