90. MRI: MOTION WITHIN THE ATOM

Question 1

1. How many types of motion particles are there in the atom?

Answer 1

• 3 types

Question 2

2. What are the 3 types of motion particles in the Atom?

Answer 2

1. NEGATIVELY CHARGED ELECTRONS
   
   • these spin on their own axis
2. NEGATIVELY CHARGED ELECTRONS
   
   • these orbit the nucleus
3. PARTICLES WITHIN THE NUCLEUS
   
   • these spin on their own axes
   • they are the Protons and the Neutrons

Question 3

3. Label this image.

Answer 3

1. Negatively charged electrons spinning on their own
   axes
2. The negatively charged electrons orbiting the nucleus
3. The neutron spinning on its own axis in the nucleus
4. The proton spinning on its own axis in the nucleus

Question 4

4. What does each type of particle motion within the atom create?

Answer 4

• it creates a Magnetic Field

Question 5

5. What 2 factors do we concern ourselves with when looking at MRIs?

Answer 5

1. THE MOTION OF THE PARTICLES
   - within the nucleus
2. THE NUCLEUS ITSELF

Question 6

6. In which direction do the Protons and the Neutrons spin about their axes in the nucleus?

Answer 6

• the direction of their spin is random
• the particles can spin clockwise or anti-clockwise

Question 7

7. What happens when a Nucleus has an even Mass Number?

Answer 7

• the directions of the spins cancel each other out
• the nucleus has NO NET SPIN

Question 8

8. What happens when the Nucleus has an odd Mass Number?

Answer 8

• the directions of the spins do not cancel each other out
• the nucleus has a NET SPIN
• this means that the nucleus spins

THIS NUCLEUS WILL ALSO HAVE A NET CHARGE:
- this is due to the charge of the Proton

Question 9

9. What happens when we have a moving charge that is unbalanced?

Answer 9

• this charge will have an odd Mass Number
• it will induce a magnetic field around itself

THIS IS DUE TO:
- the laws of Electromagnetic Induction

Question 10

10. What do the factors in this image show?

Answer 10

THE ARROW:
- shows the direction and size of the magnetic field

THE LENGTH OF THE ARROW:
- represents the strength (magnitude) of the Magnetic
Moment

THE DIRECTION OF THE ARROW:
- shows the direction of the alignment of the Magnetic
Moment

Question 11

11. What is the Total Magnetic Moment of the Nucleus?

Answer 11

• it is the vector sum of all the magnetic moments of the
  protons
• in the nucleus

Question 12

12. What do we label Nuclei that have an odd number of Protons?

Answer 12

• they are said to be Magnetic Resonance (MR) active

THIS IS BECAUSE:
- the nucleus will have an odd Mass Number
- this means that the nucleus has a net spin

Question 13

13. List 7 elements that are MR Active?

Answer 13

1. Hydrogen 1
2. Carbon 13
3. Fluorine 19
4. Phosphorous 31
5. Nitrogen 15
6. Oxygen 17
7. Sodium 23

Question 14

14. Which nucleus do we use in MRI?

Answer 14

• the MR active Hydrogen 1 nucleus

Question 15

15. Why do we use the Hydrogen 1 Nucleus?

Answer 15

1. IT IS ABUNDANT IN THE HUMAN BODY
   - it can be found in fat and water
2. IT IS A SOLITARY PROTON
   • it gives a large magnetic moment