Radioactivity

Question 1

Explain concept of linear energy transfer

Answer 1

Question 2

Explain concept of linear energy transfer

Answer 2

Question 3

What is radioactivity?

Answer 3

Radioactivity is the act of emitting radiation spontaneously.

Question 4

Why does the nucleus of an atom become unstable?

Answer 4

The nucleus of an atom becomes unstable when it either has excess nucleons or excess energy.

Question 5

How does an unstable nucleus try to become stable?

Answer 5

The nucleus tries to become stable by emitting either energy or nucleons.

Question 6

What is the smallest unit into which matter can be divided without the release of electrically charged particles?

Answer 6

The atom is the smallest unit into which matter can be divided without the release of electrically charged particles.

Question 7

What is the smallest unit of matter that has the characteristic properties of a chemical element?

Answer 7

The atom is the smallest unit of matter that has the characteristic properties of a chemical element.

Question 8

What is the basic building block of chemistry?

Answer 8

The atom is referred to as the basic building block of chemistry.

Question 9

What particles does a nucleus have?

Answer 9

A nucleus has nucleons, which include protons and neutrons.

Question 10

What is the symbol for atomic mass number?

Answer 10

The symbol for atomic mass number is ‘A’.

Question 11

What is the symbol for proton number?

Answer 11

The symbol for proton number is ‘Z’.

Question 12

What is the symbol for neutron number?

Answer 12

The symbol for neutron number is ‘N’.

Question 13

How can a specific nucleus or ‘nuclide’ be specified?

Answer 13

A specific nucleus or ‘nuclide’ can be specified using notation.

Question 14

Why is the total mass of a stable nucleus always less than the sum of the masses of its separate pieces?

Answer 14

Energy, as radiation or kinetic energy, is released during the formation of a nucleus by the ‘fusion’ of smaller nuclei, giving a net mass difference.

Question 15

What is the force that binds nucleons together?

Answer 15

The force that binds nucleons together is called the strong nuclear force.

Question 16

What is the range of the strong nuclear force?

Answer 16

The strong nuclear force is a very short-range force, essentially zero if the nucleons are more than about 10^-15 meters apart.

Question 17

Why are extra neutrons needed for the stability of high-Z nuclei?

Answer 17

Extra neutrons are needed for stability because the Coulomb force is long-range.

Question 18

What governs the decay of unstable nuclei?

Answer 18

Unstable nuclei decay, and some decays are governed by the weak nuclear force.

Question 19

What are the three types of radioactive decay?

Answer 19

The three types of radioactive decay are alpha decay, beta decay, and gamma decay.

Question 20

How do alpha and beta rays behave in a magnetic field compared to gamma rays?

Answer 20

Alpha and beta rays are bent in opposite directions in a magnetic field, indicating opposite charges, while gamma rays are not bent at all.

Question 21

What occurs during alpha decay?

Answer 21

In alpha decay, the nucleus emits a helium-4 nucleus (an alpha particle).

Question 22

When does alpha decay most often occur?

Answer 22

Alpha decay most often occurs in massive nuclei that have too large a proton to neutron ratio.

Question 23

Why is an alpha particle a stable configuration of particles?

Answer 23

An alpha particle, with its two protons and two neutrons, is a very stable configuration of particles.

Question 24

How does the decay of 210Po by alpha emission change the nucleus?

Answer 24

The decay of 210Po by alpha emission changes the nucleus to 206Pb, reducing the proton to neutron ratio and making it more stable.

Question 25

What happens to the atomic number during alpha decay?

Answer 25

The atomic number changes during alpha decay, so the original (parent) atoms and the decay-product (daughter) atoms are different elements with different chemical properties.

Question 26

What appears as the kinetic energy in alpha decay?

Answer 26

The change in binding energy appears as the kinetic energy of the alpha particle and the daughter nucleus.

Question 27

Why does most of the kinetic energy go to the alpha particle in alpha decay?

Answer 27

Most of the kinetic energy goes to the alpha particle because it has a smaller mass than the recoiling nucleus.

Question 28

When does alpha decay occur in terms of nuclear force?

Answer 28

Alpha decay occurs when the strong nuclear force cannot hold a large nucleus together.

Question 29

What is the disintegration energy in alpha decay?

Answer 29

The disintegration energy is the difference in mass between the parent nucleus and the sum of the daughter nucleus and the alpha particle.

Question 30

When does beta decay occur?

Answer 30

Beta decay occurs when a nucleus emits an electron or positron.

Question 31

What are beta particles?

Answer 31

Beta particles are electrons or positrons (electrons with a positive electric charge, or antielectrons).

Question 32

What happens during beta minus decay?

Answer 32

In beta minus decay, a neutron decays into a proton, an electron, and an antineutrino.

Question 33

What happens during beta plus decay?

Answer 33

In beta plus decay, a proton decays into a neutron, a positron, and a neutrino.

Question 34

Why do particular beta decay reactions take place?

Answer 34

These reactions take place because conservation laws are obeyed, such as the conservation of electric charge and lepton number.

Question 35

What is beta minus decay in the context of phosphorous 32?

Answer 35

Phosphorous 32 undergoes beta minus decay by transforming an excess neutron into a proton, forming the stable isotope sulphur 32.

Question 36

What is beta plus decay in the context of neon 19?

Answer 36

Neon 19 undergoes beta plus decay, having 10 protons and 9 neutrons.

Question 37

What is electron capture?

Answer 37

Electron capture is a type of beta decay where an orbital electron is pulled into the nucleus and combines with a proton to form a neutron.

Question 38

What particle is emitted during electron capture?

Answer 38

The only particle emitted during electron capture is a neutrino.

Question 39

What does the nucleus do with excess energy after electron capture?

Answer 39

The nucleus releases excess energy by emitting gamma radiation, leaving it in an excited state.

Question 40

What happens during gamma decay?

Answer 40

In gamma decay, a nucleus changes from a higher energy state to a lower energy state through the emission of electromagnetic radiation (photons).

Question 41

Does the number of protons or neutrons change in gamma decay?

Answer 41

No, the number of protons and neutrons in the nucleus does not change during gamma decay, so the parent and daughter atoms are the same chemical element.