Atomic Structure and radioactivity

Question 1

What is band theory

Answer 1

• There is a positive nucleus with protons and neutrons
• the filled bands are closest to the nucleus
• then it’s the valence band
• there may be a conduction band just outside of the atom
• spaces between the gaps are forbidden gaps

Question 2

What is the planetary (Rutherford-Bohr) model

Answer 2

• label nucleus
• have the shells labelled too like n=1, n=2 and so on
• 2n2 is the maximum number of electrons allowed in each shell

Question 3

What is atomic ionisation

Answer 3

• When energy comes into the atom and overcomes the binding energy of an electron
• this electron is given energy and escapes the atom
• this causes an electron cascade and electromagnetic radiation to occur
• the energy is equal to the difference in the binding energy of the shells

Question 4

What is excitation

Answer 4

• the electron is given energy and moves to a higher energy level when the energy exceeded the binding energy
• it then falls back down and electromagnetic radiation equal to the difference in binding energies is released

Question 5

What is Pauli exclusion principle

Answer 5

• this is that no two electrons can have exactly the same physical properties due to a cluster of different energy states
• so even two electrons in the same shell would differ in some way from different spin or magnetic moment

Question 6

What is isomeric transition

Answer 6

This is a transition from a meta stable state to a ground state and happens due to the emission of energy

Question 7

What is an Auger electron and how is it formed

Answer 7

•ionisation of inner shell electrons causing the production of characteristic photons can sometimes lead to energy being transferred to another orbital electron which is ejected and known as an auger electron

Question 8

What is the difference between a positron, and a negatron

Answer 8

They have the same mass and are opposite so a positron is the antiparticle of an electron with a positive charge and a negatron has a negative charge

Question 9

What is the binding energy for K shell electrons

Answer 9

69.5 keV

Question 10

What is meant by isomeric transition?

Answer 10

• It’s after a Beta process where there is an unstable nucleus
• A spontaneous emission of gamma energy at a specific energy occurs
• It is a transition of a meta stable state to a ground state with the emission of energy
• There is a specific half life to this decay