4.4 CHAPTER 4. THE ATOM
and situated in the middle of the atom.How small is the nucleus? ESAAX
The nucleus of an atom is very small. We can
compare an atom with a soccer stadium. If
the whole atom is as big as a soccer stadium,
the nucleus is only the size of a pea in the
middle of the stadium! This should help you
see that the atom is mainly made up of empty
space. If you removed all the empty space
from the atoms in your body, you would be-
come the size of a grain of salt!A stadiumPicture by Shine 2010 on Flickr.comRelative atomic mass ESAAY
DEFINITION: Relative atomic mass
The relative atomic mass of an element is the average mass of all the natu-
rally occurring isotopes of that element. The units for relative atomic mass
are atomic mass units.The relative atomic mass of an element is the number you will find on the periodic table.Structure of the atom ESAAZ
As a result of the work done by previous scientists on atomic models, scientists now have
a good idea of what an atom looks like. This knowledge is important because it helps us
to understand why materials have different properties and why some materials bond with
others. Let us now take a closer look at the microscopic structure of the atom (what the
atom looks like inside).70 Chemistry: Matter and Materials