E = mc^2

Question 1

Nuclear fission define

Answer 1

Neutrons bombard nuclei of heavier elements to split it and release energy.

Free neutrons then collide with other atomic nuclei, starting a chain reaction

Question 2

Nuclear fusion define

Answer 2

Fuse two or more light elements

Releases a huge amount of energy

Question 3

Einstein’s theory of relativity

Answer 3

When an object accelerates, it’s inertial mass increases

If the mass of an object is specified, assume it is the rest mass.

Question 4

Define mass defect and binding energy

Answer 4

Neutrons and protons bound in a nucleus was LESS than the sum of their masses
Difference is the mass defect

Small amount of matter pulled into nucleus converted to tremendous amount of energy = binding energy

=energy needed to separate a nucleus into its individual constituent parts

Question 5

ΔE = Δmc^2

Answer 5

Mass defect Δm used to find binding energy E or vice versa

=Work

Can divide energy by number of nucleons (protons and neutrons) to find energy per nucleon

Question 6

How does binding energy relate to stability of nucleus

Answer 6

More mass missing = higher binding energy = more stable

Iron is the most stable as it has the highest binding energy PER NUCLEON of any element

Hence nuclei smaller than Fe fuse, nuclei larger than Fe undergo fission

Question 7

What forces act within the Fe nucleus?

Answer 7

Strong nuclear vs electrostatic repulsion (coulombic force)

Larger elements - ‘outside’ nucleons experience greater electrostatic repulsion and break down

As the strong nuclear force acts only over 10^-15m, the size of the Fe nucleus

Question 8

Conservation rules

Answer 8

Mass number

Atomic number (use these for writing equations)

Charge

Momentum

Mass-energy

Question 9

Radioactive decay types and the effects on atomic stability

Answer 9

Alpha

Beta

Gamma