Exam 2: Nuclear Reaction

Question 1

Nucleons

Answer 1

Particles in the nucleus

Question 2

Mass number

Answer 2

Total number of nucleons

Question 3

Nuclide

Answer 3

Atom with specific number of protons and neutrons (think of an element but this only pertains to nuclear chemistry)

Question 4

Why does radioactive decay occur?

Answer 4

Nuclides have unstable nuclei

Question 5

What is the “parent” nuclide?

Answer 5

The nucleus that is undergoing radioactive decay

Question 6

What is the “daughter” nuclide?

Answer 6

The new nucleus that is made

Question 7

What happens when a nuclide decays?

Answer 7

It usually changes into a nuclide of a different element. It spontaneously emits radiation in which a particle or energy is emitted. The intensity of the radiation is not affected by temperature, pressure, or other physical and chemical conditions.

Question 8

What are the three natural types of radioactive emission?

Answer 8

Alpha particles are identical to helium-4 nuclei. Beta particles are high-speed electrons. Gamma rays are very high-energy photons.

Question 9

What happens during alpha decay?

Answer 9

The nucleus emits an alpha particle and it acquires two electrons from an atom(s) at the end of its parts to become a helium atom

Question 10

What is an alpha particle?

Answer 10

Essentially a helium nucleus (two protons and two neutrons) which is very stable

Question 11

What is transmutation?

Answer 11

The process of transforming one element to another

Question 12

How far do alpha particles travel?

Answer 12

They do not travel far in the air before being absorbed

Question 13

What are alpha particles used in?

Answer 13

They are used in smoke detectors (largest and least penetrating)

Question 14

What is beta decay?

Answer 14

Involves the ejection of a beta particle from the nucleus

Question 15

What happens to neutron during beta decay?

Answer 15

Neutron is converted to a proton, which remains in the nucleus, and a beta particle is expelled

Question 16

What is a beta particle?

Answer 16

Like an electron

Question 17

What is positron emission?

Answer 17

The emission of a beta(+) particle from the nucleus; has a +1 charge

Question 18

What is a positron?

Answer 18

The antiparticle of the electron (anti-electron)

Question 19

What happens to the proton during positron emission?

Answer 19

Proton in the nucleus is converted into a neutron and a positron is emitted

Question 20

What is electron capture?

Answer 20

Occurs when an inner orbital electron is pulled into the nucleus

Question 21

What is the result of an electron capture?

Answer 21

No particle emission, but atom changes (same result as positron emission)

Question 22

What happens to proton during electron capture?

Answer 22

Proton combines with the electron to make a neutron

Question 23

What are the particle changes of beta emission, positron emission, and electron capture?

Answer 23

Beta: neutron changing into a proton
Positron: proton changing into a neutron
Electron: proton changing into a neutron

Question 24

Draw the particle changes of beta emission, positron emission, and electron capture.

Answer 24

See slide 24 of LEC 27

Question 25

What is gamma radiation?

Answer 25

Involves the emission of electromagnetic energy (similar to light energy) from an atom’s nucleus, as the protons and neutrons become more tightly bound; high energy photons

Question 26

What is true about emission during gamma decay?

Answer 26

No particles are emitted during gamma radiation, so gamma radiation does not itself cause the transmutation of atoms (gamma rays have no mass or charge)

Question 27

What is true about the emission of gamma radiation?

Answer 27

Gamma radiation is often emitted during, and simultaneous to, alpha or beta radioactive decay

Question 28

What is the common example of gamma radiation?

Answer 28

X-rays; emitted during the beta decay of cobalt-60

Question 29

What are the characteristics of gamma rays?

Answer 29

Very penetrating; they can be most efficiently absorbed by a relatively think layer of high-density material such as lead

Question 30

How do you balance a nuclear reaction?

Answer 30

Balance the total of all atomic numbers and total of all mass numbers for the products and reactants

Question 31

In nuclear reactions, how are the rate of reactions affected?

Answer 31

They are normally not affected by temperature, pressure, and catalysts

Question 32

What is the difference between chemical and nuclear reactions in terms of energy?

Answer 32

Chemical reactions absorb and release small amounts of energy while nuclear reactions absorb and release tremendous amounts of energy

Question 33

What particles are involved in chemical or nuclear reactions?

Answer 33

In chemical reactions, only electrons are involved while protons, neutrons, electrons, and other elementary particles are involved in nuclear reactions

Question 34

What happens during a nuclear reaction?

Answer 34

Elements (or isotopes of elements) are converted from one another

Question 35

How are radioactive substances used?

Answer 35

Used as tracers (ex: blood flow or brain imaging); usually involves the formation of an image; administered to treat disease or provide pain relief