Nuclear Radius

Nuclear Physics

Homework Research and explain how electron

diffraction can be used to determine the radius of the nucleus (6 Marks)

Past Paper Question on today’s material.

Complete both by Next Lesson, next Monday, Period 5.

Learning Objectives State and use the equation for

dependence of radius on nucleon number.

Calculate nuclear density. Recall the implications of the high

nuclear density compared to atomic density.

Equation Dependence of

radius on nucleon number:- 3/1

0ArR [The term A1/3 means the cube root of A, the nucleon number.  The term r0 is a constant with the value 1.4 × 10-15 m.  R is the nuclear radius.] What physical quantity is r0?

Rearrange in the form of A=.Try working out R for Gold (A =197 ) and Carbon (A=12)

Nuclear Density Radius of a carbon nucleus ~ 3.2 x 10-15m. Radius of a gold nucleus ~ 8.1 x 10-15m.

Mass of a carbon nucleus ~ 2.00 x 10-26kg. Mass of a gold nucleus ~ 3.27 x 10-25kg.

What are the densities of the nuclei?

Nuclear Density Density of carbon nucleus ~ 1.46 x 1017 kg m-3. Density of gold nucleus ~ 1.47 x 1017 kg m-3.

Very high! One teaspoon = 500 million tonnes. So pretty much the same, regardless of

element.

Ext: Work out mass of neutron star based on this density. How does it compare to solar mass?

Nuclear Density Nuclear density >> Atomic Density

This implies:- Most of an atom’s mass is in its nucleus. The nucleus is small compared to the

atom. An atom must contain a lot of empty

space.

Example Exam Questions Q1: (a)If a carbon nucleus containing 12

nucleons has a radius of 3.2 x 10-15m, what is r0?

(b) Calculate the radius of a radium nucleus containing 226 nucleons.

(c) Calculate the density of a radium nucleus if its mass is 3.75 x 10-25 kg.

Q2: A sample of pure gold has a density of 19300 kg m-3. If the density of the gold nucleus is 1.47 x 1017kg m-3 discuss what this implies about the structure of a gold atom.

Learning Objectives State and use the equation for

dependence of radius on nucleon number.

Calculate nuclear density. Recall the implications of the high

nuclear density compared to atomic density.