Nuclee-ides

Question 1

Describe the three forces that act on particles within the nucleus and how they affect the stability of the nucleus.

Answer 1

• Gravitational forces between any two objects that have mass: Weak attractive force between all nucleons; Relatively long range.
• Electrostatic forces between charged particles: Strong repulsive force between like charged particles (protons); Relatively long range.
• Nuclear forces between nucleons (protons and neutrons): Strong attractive force between all nucleons; Extremely short range

Question 2

Enriched uranium

Answer 2

uranium-235 isotope concentration greater than its natural value

Question 3

Depleted uranium

Answer 3

uranium-235 isotope concentration less than its natural value (0.72%)

Question 4

Mass Defect (∆m)

Answer 4

difference between mass of atom and sum of masses of its parts

Question 5

Binding Energy (BE)

Answer 5

amount of energy that must be supplied to nucleus to completely separate its nuclear particles (nucleons). Also defined as amount of energy that would be released if nucleus was formed from separate particles

Question 6

Describe Ionization

Answer 6

Removing an electron from its orbit

Question 7

Describe ionization energy

Answer 7

The energy required for ionization

Question 8

Describe the differences between X-ray and Gamma-ray

Answer 8

Defined by their sources – identified by wavelength

• X-rays are emitted by electrons; a discrete bundle of electromagnetic energy emitted when an excited atom transitions to a lower-energy excited or ground state
• gamma rays are emitted from the nucleus – shorter wavelength; Nucleons in an excited nucleus transition towards their lowest energy configuration and emit a discrete bundle of electromagnetic radiation called a gamma ray (ˠ)

They are both photons and undergo similar interactions

Question 9

Conservation of Electric Charge

Answer 9

Conservation of electric charge implies that charges are neither created nor destroyed. Single positive and negative charges may neutralize each other. Possible for a neutral particle to produce one charge of each sign.

Question 10

Conservation of Mass Number

Answer 10

Conservation of mass number does not allow a net change in the number of nucleons. However, the conversion of one type of nucleon to another type (proton to a neutron and vice versa) is allowed.

Question 11

Conservation of Mass and Energy

Answer 11

Conservation of mass and energy implies that the total of the kinetic energy and the energy equivalent of the mass in a system must be conserved in all decays and reactions. Mass can be converted to energy and energy can be converted to mass, but the sum of mass and mass-equivalent energy must be constant.

Question 12

Conservation of Momentum

Answer 12

Conservation of momentum is responsible for the distribution of the available kinetic energy among product nuclei, particles, and/or radiation. The total amount is the same before and after the reaction even though it might be distributed differently among entirely different nuclides and/or particles.

Question 13

Given the stability curve on the Chart of the Nuclides, determine the type of radioactive decay that the nuclides in each region of the chart will typically undergo.

Answer 13

• Nuclides below and to the right of the line of stability usually undergo β- decay
• Nuclides above and to the left of the line of stability usually undergo either β+ decay or electron capture.
• Nuclides likely to undergo alpha (α) decay are found in the upper right hand region
• Some exceptions apply especially in the region of heavy nuclides

Question 14

Given a Chart of the Nuclides, describe the radioactive decay chain for a nuclide. (see page 44 of chart of nuclides)

Answer 14

• alpha: Go down 2 and left 2 boxes (or diagonally down and left 2, depending how you look at it).
• b-: Go up and to the left 1 (diagonally up and to the left)
• b+: Go down and to the right 1 (diagonally down and left)

Question 15

Determine the half-life if decay constant is known

Answer 15

t_(1/2)=0.693/λ

Question 16

Determine the decay constant if necessary

Answer 16

Use equation:

λ=0.693/t_(1/2)