The Size of the Atom
Using scattering and diffraction methods, we know that the radius of an atom is 0.05nm or 5x10^-11m and the radius of the smallest nucleus is 1fm or 1x10^-15
Particles that make up the nucleus are protons and neutrons alternatively called nucleons. The number of nucleons in an atom is the nucleons/mass number. The more nucleons added to the nucleus the bigger it gets.
A graph to show how nuclear radius increases with increasing nucleon number will be a line curving upwards and to the right.
A graph to show how nuclear radius is directly proportional to the cube root of the nucleon number will be a straight line through the origin.
Calculating the Radius of a Nucleus
r: radius, m
ro: constant: 1.4x10^-15m
A: nucleon number
1/3 is also the same as the cube root
Calculating Nuclear Density
All nucleons take up about e same volume in a nucleus. Because they all have nearly the same mass which also means they all have a similar density, p.
Density example when given the mass:
Understanding Nuclear Density
Nuclear density is significantly larger than atomic density - this suggest three important facts about the structure of an atom:
-most of the atoms mass is in its nucleus
-the nucleus is mall compared to the atom
-an atom must contain a lot of empty space