Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: thedoc on 31/03/2016 02:50:01

Title: What is the size difference between atoms of different elements?
Post by: thedoc on 31/03/2016 02:50:01

Martin Fennell asked the Naked Scientists:
   Hi

How much bigger are atoms of different elements?

For example, is a helium atom twice the size of a hydrogen atom?

Thanks

Martin
What do you think?

Title: Re: What is the size difference between atoms of different elements?
Post by: evan_au on 31/03/2016 09:44:14

Have a look at: http://crystalmaker.com/support/tutorials/crystalmaker/atomic-radii/index.html

It's a bit more laborious, but you can also look up each element in Wikipedia, and it will give the size of the atom in the information box on the right-hand side (sometimes several different sizes, depending on the method used to measure it, or what element it is bonded with).

Hydrogen: covalent radius 31±5pm; Van der Walls radius 120pm See: https://en.wikipedia.org/wiki/Hydrogen
Helium: covalent radius: 28pm; Vand der Waals radius: 140pm. https://en.wikipedia.org/wiki/Helium

Note also that the size of an atom varies a bit depending on whether it is a neutral atom or a charged ion.