Atomic Physics
IN 1897 , JJ Thomson discovered the electron. After the development of the planetary model of the atom in 1911, Rutherford proposed another subatomic particle and named it the proton, in 1919.
However, there were still limitations in that planetary model , in terms of mass. Why were there heavier atoms? They could have more protons, bu they did not have a significant increase in charge.Rutherford proposed a particle that was possible a proton and electron joined together.The stage was set for work that eventually culminated in the discovery of the neutron by James Chadwick.
In the second half we discuss the principles of radioactivity: the types of radioactivity as well as the physics principles that govern it.
However, there were still limitations in that planetary model , in terms of mass. Why were there heavier atoms? They could have more protons, bu they did not have a significant increase in charge.Rutherford proposed a particle that was possible a proton and electron joined together.The stage was set for work that eventually culminated in the discovery of the neutron by James Chadwick.
In the second half we discuss the principles of radioactivity: the types of radioactivity as well as the physics principles that govern it.
1. 1897 - JJ Thomson and his electron
1a. 1909 - Millikan's Oil Drop Experiment
2. 1911 - Rutherford and the atomic planetary model
3. 1913 - The Bohr model of the atom
4. 1932 - Chadwick and the discover of the neutron
We now turn our attention to radioactivity.
In the late 1890s and Henri Becquerel, and then later Pierre and Marie Curie discovered that certain materials emitted radiation.
This began understanding of radioactivity spontaneous emission of particles and or energy from matter. The following videos starts by examining what radioactivity is, and then examined for physics underpinning it
In the late 1890s and Henri Becquerel, and then later Pierre and Marie Curie discovered that certain materials emitted radiation.
This began understanding of radioactivity spontaneous emission of particles and or energy from matter. The following videos starts by examining what radioactivity is, and then examined for physics underpinning it
5. What is radioactivity?
6. Half Life Explained
7. Understanding Mass Defect and Binding Energy
Mass Defect
When nucleus transmutes, such as in the case of alpha or beta decay, energy is released. But where does that energy come from? (It also occurs in nuclear fission and fusion, which we will discuss shortly)
The answer simply is from the matter itself.
Like a chemical reaction where you have reactants and products, so too, in nuclear reactions you have a reactant or reactants which results in the production of the products.
During the process of the nuclear reaction there is less mass in the products than the reactants.
This seems to violate one of the conservation laws: one of the conservation of matter. But the fact is the mass lost is converted into energy - the mass defect.
Some more correctly the conservation laws is about the conservation of mass-energy, mass is just the concentration of energy by way of E=mc^2
This is referred to as the mass defect.
When nucleus transmutes, such as in the case of alpha or beta decay, energy is released. But where does that energy come from? (It also occurs in nuclear fission and fusion, which we will discuss shortly)
The answer simply is from the matter itself.
Like a chemical reaction where you have reactants and products, so too, in nuclear reactions you have a reactant or reactants which results in the production of the products.
During the process of the nuclear reaction there is less mass in the products than the reactants.
This seems to violate one of the conservation laws: one of the conservation of matter. But the fact is the mass lost is converted into energy - the mass defect.
Some more correctly the conservation laws is about the conservation of mass-energy, mass is just the concentration of energy by way of E=mc^2
This is referred to as the mass defect.
And it is that mass difference that converts to energy by way of Einstein's famous equation
But in nuclear physics, is is more helpful to to use a non SI unit for mass, as well as for energy
So instead of using the joule (J) for energy we can use the electron volt (eV)
And for mass , instead if using the kilogram, we use the atomic mass unit (u).
The video covers this
Before you continue however, make sure you are familiar with the electron volt (eV) as a unit of energy - If not, please review here.
But in nuclear physics, is is more helpful to to use a non SI unit for mass, as well as for energy
So instead of using the joule (J) for energy we can use the electron volt (eV)
And for mass , instead if using the kilogram, we use the atomic mass unit (u).
The video covers this
Before you continue however, make sure you are familiar with the electron volt (eV) as a unit of energy - If not, please review here.
8. Strong Nuclear Force Explained
When we think of nuclear processes so far we have discussed radioactive decay, that is alpha, beta and gamma decay.
As well producing the nuclear products, energy is also released. However, there are other nuclear processes that release energy but do not involve radioactive decay.
In brief, fission is the process by which a large atom can be broken into two smaller atoms with the result of the release of energy. In fusion, two smaller atoms are combined to produce one larger atom but also release excess energy.In both cases these processes can be under uncontrolled, releasing the energy very quickly, or controlled, allowing the energy to be released progressively.
As well producing the nuclear products, energy is also released. However, there are other nuclear processes that release energy but do not involve radioactive decay.
In brief, fission is the process by which a large atom can be broken into two smaller atoms with the result of the release of energy. In fusion, two smaller atoms are combined to produce one larger atom but also release excess energy.In both cases these processes can be under uncontrolled, releasing the energy very quickly, or controlled, allowing the energy to be released progressively.