Nuclear Physics

Question 1

Define Atom

Answer 1

The smallest part of an element which retains its characteristics.

Question 2

What are the Subatomic Particles that make up an atom?

Answer 2

Protons: +charged particle located in the nucleus
Neutrons: uncharged particle located in nucleus (p+ and n° are similar in size and mass- 1amu)
Electrons: -charged particle, very tiny, mass is almost nothing.

Question 3

What is an Ion?

Answer 3

An atom that has lost/gained electrons in order to become stable.

Question 4

What are the 4 fundamental forces which affect “things”?

Answer 4

Gravitational, Electromagnetic, Strong Nuclear, Weak Nuclear Forces

Question 5

What is Proper Nuclear Notation?

Answer 5

Atomic# on bottom, total# of particles in nucleus on top

Question 6

What are isotopes?

Answer 6

Different versions of an element with same #of p+ but different #of n°

Question 7

What is Ionizing Radiation?

Answer 7

Waves/particles carrying enough energy to remove an electron from an atom and turn it into an ion. These can cause cell damage or alter DNA so they don’t replicate normally.

Question 8

What is Nuclear Radiation?

Answer 8

Ionizing radiation emitted from the nucleus of an atom. Occurs when an unstable nucleus sends out particles and em radiation.

Question 9

What is Alpha Decay?

Answer 9

Alpha particle is emitted from nucleus changing #of p+ and n°. A.p. is basically the nucleus of a helium atom. Occurs when nucleus is particularly large and strong nuclear force is not strong enough at larger range to hold nucleus together. (4a2)

Question 10

What is Beta Decay?

Answer 10

Beta particle is emitted from nucleus in odd transmutation. Occurs when atom contains too many neutrons causing it to be unstable. An n° changes into p+ and and e-. [°B(-1)]

Question 11

What is Gamma Decay?

Answer 11

Occurs when particles of nucleus are in an excited/unstable arrangement. As particles move to lower energy lvl, a high energy photon of light is emitted called gamma photon. Doesn’t alter # of p+/n°. No mass, no charge, travels at speed of light, penetrate most objects.

Question 12

What is Radioactive Decay?

Answer 12

A spontaneous (therefore unpredictable) process tht is impossible to predict unless there is a reasonably large sample of radioactive isotopes.

Question 13

What is Half Life?

Answer 13

How long it will take for half of a substance to decay. M=Mo(1/2)^(t/h) If looking for t/h - log or common base.

Question 14

What is Mass Energy Equivalency?

Answer 14

Products are 1.7x10^-31 kg lighter. E=mc^2

Question 15

What is Nuclear Fission?

Answer 15

A massive nucleus splits into two lighter nuclei.

Question 16

What is Spontaneous Fission?

Answer 16

A single highly unstable nucleus splits into two smaller lighter nuclei. Occurs in very heavy nuclei with atomic masses above 230. (The total mass of the two daughter nuclei is less than that of the parent… thus a tiny bit of mass has been converted into a huge amount of energy.)

Question 17

What is Induced Fission?

Answer 17

A neutron (with no charge) can easily pass through the electron cloud of a large atom and collide with its nucleus. This collision creates highly unstable isotope that will usually split into two (nearly identical) lighter nuclei. In addition to the two lighter nuclei, three free neutrons are also released. These newly released nuclei are often still unstable and may undergo alpha, beta or gamma decay.

Question 18

What are some applications of Nuclear Fission?

Answer 18

Nuclear power plants used a highly controlled version of nuclear fission to produce electrical energy. Nuclear Bombs dropped on Hiroshima and Nagasaki at the end of World War II were fission bombs using highly enriched (and thus unstable) uranium.

Question 19

What is a Radioactive Decay Series?

Answer 19

Some fission reactions set of a series of reactions which may last for a few seconds or thousands of years. In a radioactive decay series, each daughter nucleus continues to decay (again and again) until it becomes stable.

Question 20

What is Nuclear Fusion?

Answer 20

Two nuclei combine to form a more massive nucleus.

Question 21

How is Nuclear Fusion achieved?

Answer 21

Nuclear Fusion involves the “fusing” (joining) of two smaller nuclei together to form one larger nucleus. The goal of fusion is to get the two small nuclei close enough together so that the strong nuclear force takes over and pulls them together. This is very difficult to achieve due to the electrostatic repulsion of the two positively.

Question 22

What are Nuclear Chain Reactions?

Answer 22

A series of nuclear fissions that start with one reaction which produces free neutrons which then cause more fission reactions and the cycle continues.

Question 23

What are Thermonuclear Reactors?

Answer 23

A nuclear reactor is a device in which nuclear chain reactions are initiated and controlled. The reactions heat water to produce steam used to generate electricity.

Question 24

What is enriched Uranium?

Answer 24

Uranium that has gone through high-speed centrifuges to increase the concentration of U-235, the uranium isotope required for nuclear reactors as they are the only fissile isotope in existence in nature.

Question 25

What are Control Rods?

Answer 25

Control rods are made of an element that absorbs neutrons without undergoing fission and can be inserted into the reactor and thus control the rate of fission in a reactor.

Question 26

What is Heavy Water?

Answer 26

(D2O) Water that contains high proportion of isotope deuterium (Hydrogen-2) which cause neutrons to give up a lot of energy, slowing them but not stopping them.

Question 27

What is a Coolant?

Answer 27

A liquid (water) that flows into, through, and out of the reactor core, removing thermal energy from the core by conduction and transferring the energy to the boiler to make steam.

Question 28

What does CANDU stand for?

Answer 28

CANada Deuterium Uranium

Question 29

How are CANDU reactors different from other reactors?

Answer 29

They use natural uranium rather than the more costly enriched uranium in fuel pellets. They can also make their own fuel in a neutron absorption breeding process.

Question 30

How is nuclear waste disposed of?

Answer 30

When spent fuel rods are taken out of a reactor, they are stored underwater in large pools of water which cools the spent fuel and shields workers from its radiation. After a few years they can be removed safely and stored in concrete containers which are shipped to dedicated storage facilities while being closely monitored.