I’m in third grade and I now have chemistry and physics. In those courses I learn about atoms and molecules (it is clear to me what the difference is). I now wonder how big an atom is and a molecule or what the volume of those two is. If that differs from atom to atom and molecule to molecule, would you be so kind as to give me some examples?
Answer
Dear Zeger,
I hope you like those subjects a bit, because although you do have to make a certain effort to understand everything, these subjects allow us to understand the world around us. Atoms, as you know, are the building blocks of all matter and they very often cluster together in molecules. Atoms are also, from our perspective, extremely small. So small that it is not easy to imagine. Imagine the thickness of a hair (about 100 micrometers) and take one-thousandth of that (0.1 micrometers). If you want to achieve that thickness with fluorine atoms, you can still stack 1000 on top of each other, in other words: a fluorine atom has a diameter of 0.1 nanometer or 1 Angstrom. The big difference indeed from atom to atom, eg the smallest atom of hydrogen has a diameter of half an Angstrom. A Cesium atom is ten times larger, viz. 5 Angstroms. On the website http://en.wikipedia.org/wiki/Atomic_radius you will find an overview of all atomic radii (see table at the end of the article). The radii are expressed in picometers and this is a measure of length that is 100 times smaller than an Angstrom, eg 5 Angstroms as diameter gives 2.5 Angstroms as radius and this is 250 picometers. To calculate volume, you simply have to assume that each atom is actually spherical. I hope this suffices.
Regards
Answered by
Prof. dr. Dirk Vanderzande
Agoralaan University Campus Building D BE-3590 Diepenbeek
http://www.uhasselt.be/
.