Atom size and structure

Question

If someone wanted to build a scale model of the atom with a nucleus 1.00m in diameter, how far away would the nearest electron need to be?

Answer 1

The electron isn't really in a single place. Nonetheless:

From http://en.wikipedia.org/wiki/Atomic_nucl... , you will find out that the nucleus size varies on about an order of magnitude, from 1.5 fm to 15 fm (that's femtometers: milli, micro, nano, pico, femto. 1 fm = 10^-15 m.)

Hydrogen atoms are roughly 25 pm in radius; helium atoms are closer to 30 pm. If that's a good number for the radius of the innermost electrons, then for these two sizes:

(electron radius) / (nucleus diameter) = 25 000 fm / (1.5 fm) ~= 17,000.

(electron radius) / (nucleus diameter) = 25 000 fm / (15 fm) ~= 1,700.

So, we can say that if your scale model had a nucleus of 1m in diameter, then the electron shell for the innermost electron would be between 1.7 km and 17 km away, depending on the atom and such.

Answer 2

The size of the nucleus is a little over cuberoot (N) femtometers (10^-15 meters), where N is the number of nucleons.

The characteristic size of the smallest orbital in hydrogen is about the bohr radius (look it up on wiki if you don't know it).  Bigger atoms with more nuclear charge keep the electrons in the inner orbit tighter of course, but let's stick to hydrogen--just a proton and an electron.

So the size of your model for hydrogen would be (very roughly):

1 meter * bohr radius / 1 fm

And it would have to be about twice as big as that if you wanted to make a decent picture of what the orbital looks like--it's like a spherical cloud that is densest in the middle and less dense far away.  It's actually infinitely big, but the electron is typically about a bohr radius away at any given time and rarely strays more than a few bohr radii.

Answer 3

in a different building.

if the nucleus of an atom were the size of a pea, the electron shell would be larger than a football stadium.  

Answer 4

Really far away.