Question

Question:

The Van der Waals radii of O,N,Cl,F and Ne increases in the order?

Chemistry Periodic Properties and Variations of Properties - Physical and Chemical Size of the Atom or Ion

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Solution:

Van der Waals radius decreases along a period from left to right due to increase in nuclear charge and then increases at noble gasses.

Chlorine being the element from the third period and rest from the second period has the largest size.

My question is if the radii at noble gases increases then in the ascending order how is neon placed before fluorine ? Plz explain. Thank you.

Answer 1

Normally atomic radii decrease going across a period due to contraction from an increased pull of the higher electron count. However neon is a noble gas and cannot be measured the same way. The atomic radius is determined through covalent bonds which tend to increase contraction of individual atoms due to the pull from bonding. Noble gases’ atomic radius needs to be determined by Van Der Waals forces because neon doesn’t form a bond and therefore is not as contracted as bonded elements.