Answer 1:
An interesting question! It really makes you
think about what matter is actually made of.
The approximate size of an atom is about
10^{10} m (this is for fairly large
atoms). Here, I use something called scientific
notation where powers of 10 are represented
with exponents, so 10^{10} m=
0.0000000001 m = 1/10,000,000,000 m. That's tiny!
But the nucleus is even smaller at only around
10^{15} m; it is five orders of magnitude
smaller than the atom itself at around
0.000000000000001 m. (There are so many zeros, I
had to count thrice!)
How to imagine a number this small?
Take a look at the tip of one of your hair
strands. On average, people's hair is around 100
microns (i.e., 106 m). You could fit
about one million atoms just across the diameter
of your hair!
What about the size of nucleus relative to
the atom?
Imagine that you were the nucleus. A person
is about 1 m across. The boundary of where the
edge would be is about 10^{5} m = 100,000
m away. That's almost 2.5 marathons (or 65 miles)!
I don't think you could see that far.
So the nucleus only takes up a small fraction
of the volume of an atom. Does this mean the
atom is mostly empty space? Sort of.
The nucleus is surrounded by electrons
sloshing around, but these electrons are not
particles that whizz about. Once you get to atomic
length scales, quantum mechanics starts to
kick in and you need to start describing things as
having wavelike character.
The key notion is there is a certain
probability of finding the electrons somewhere,
and some places are more likely than others. You
can see the beautiful complexity that electrons
fill atomic orbitals and slosh about around the
nucleus
here
What really causes interesting properties to arise
is really the interaction of all these electrons
and nuclei when put in different configurations
and crystal structures! And this is known as the
study of materials science.
Hope this helps,
Best,
