1. Nuclear Radius Nuclear Physics

2. 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.

3. 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.

4. Equation Dependence of radius on nucleon number:- [The term A 1/3 means the cube root of A, the nucleon number. The term r 0 is a constant with the value 1.4 × 10 -15 m. R is the nuclear radius.] What physical quantity is r 0 ? Rearrange in the form of A=. Try working out R for Gold (A = 197 ) and Carbon (A=12)

5. Nuclear Density Radius of a carbon nucleus ~ 3.2 x 10 -15 m. Radius of a gold nucleus ~ 8.1 x 10 -15 m. Mass of a carbon nucleus ~ 2.00 x 10 -26 kg. Mass of a gold nucleus ~ 3.27 x 10 -25 kg. What are the densities of the nuclei?

6. Nuclear Density Density of carbon nucleus ~ 1.46 x 10 17 kg m -3. Density of gold nucleus ~ 1.47 x 10 17 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?

7. 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.

8. Example Exam Questions Q1: (a)If a carbon nucleus containing 12 nucleons has a radius of 3.2 x 10 -15 m, what is r 0 ? (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 10 17 kg m -3 discuss what this implies about the structure of a gold atom.

9. 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.