Structure and Properties of the Nucleus

Phosphorescent materials continue to glow after the lights are turned off. How can you use the model of an atom to explain this?

Structure and Properties of the Nucleus

NucleonsProton is the nucleus of the simplest atom, hydrogen. It has positive charge (+e) and mass mp=1.6726x10-27 kg.

Neutron is electrically neutral and has mass mn=1.6749x10-27 kg

Nuclei that contain the same number of protons but different number of neutrons are called isotopes.

Nuclear Radii

3/115 )102.1( Amr

Atomic Mass Unit

227 /5.931106605.11 cMeVkgu

Binding Energy and Nuclear Forces

The total mass of a stable nucleus is always less than the sum of the masses of its constituent protons and neutrons.

The total energy represents the amount of energy that must be put into a nucleus in order to break it apart into its constituent protons and neutrons.

To be stable, the mass of nucleus must be less than that of constituent nucleons, so that energy input is needed to break it apart.

Radioactivity

Radioactivity is the result of the disintegration or decay of instable element.

Alpha Decay

Smoke Detectors

parent daughter

Transmutation

Q-Value

The energy released is called the disintegration energy, Q or Q-value:

2)( cMMMQ DP

Beta Decay

Gamma Decay

1. Which of the three types of radiation will interact with electric field?

2. Why do beta rays and alpha rays deflect in opposite directions when moving through a magnetic field?

Baby-Quiz

1. Where would you most likely find an electron in the first excited state for a one-dimensional box?

2. Why do some minerals glow when they are illuminated with ultraviolet light?

3. The wavelength of red light is 600 nm. An electron with a speed of 1.2 km/s has the same wavelength. Will the electron look red? Explain.

4. An electron and proton have the same speeds. Which has the longer wavelength? Why?