4.4 Nuclear Stability and Radioactivity

Question 1

What is the nuclear force?

Answer 1

Force that holds protons and neutrons together in the nucleus

Question 2

What is radioactivity?

Answer 2

Spontaneous disintegration of an unstable nuclide by a first order rate law

Question 3

What are the three types of radioactive decay?

Answer 3

Alpha
Beta
Gamma

Question 4

What is alpha decay?

Answer 4

Occurs when a large nucleus wants to become more stable by reducing the number of protons and neutrons; will emit an alpha particle

Question 5

What is an alpha particle?

Answer 5

Two protons and two neutrons

Question 6

What happens to atomic number and atomic mass after alpha decay?

Answer 6

Atomic number reduced by two
Atomic mass reduced by four

Question 7

What are the three types of beta decay?

Answer 7

Beta negative
Beta positive
Electron capture

Question 8

What is beta negative decay?

Answer 8

Unstable nucleus contains too many neutrons; will convert neutron into a proton and an electron

Question 9

What happens to the atomic number and atomic mass of an atom after beta negative decay?

Answer 9

Atomic number is plus one
Atomic mass remains the same

Question 10

What is beta positive decay?

Answer 10

Unstable nucleus contains too few neutrons; converts a proton into a neutron and positron

Question 11

What is a positron?

Answer 11

Electrons antiparticle; basically an electron with a positive charge

Question 12

What happens to the atomic number and atomic mass after beta positive decay?

Answer 12

Atomic number is one less
Atomic mass remains the same

Question 13

What is electron capture?

Answer 13

Method for an unstable nucleus to increase number of neutrons is to gain an electron from a nearby electron shell and use it in the conversion of a proton to a neutron

Question 14

What happens to the atomic number and atomic mass after electron capture?

Answer 14

Atomic number is reduced by one
Atomic mass remains the same

Question 15

What is gamma decay?

Answer 15

A nucleus is in an excited state from alpha or beta decay and emits energy in the form of electromagnetic radiation or photons when it relaxes to its ground state

Question 16

What are gamma rays?

Answer 16

High energy, short wavelength form of electromagnetic radiation emitted by the nucleus of an atom that carries off some of the energy generated in a nuclear reaction

Question 17

What is half-life of an atom?

Answer 17

Time it takes for one half of a radioactive substance to decay

Question 18

What is nuclear binding energy?

Answer 18

Energy that was released when the individual nucleons were bound together by the strong force to form the nucleus

Question 19

What is mass defect?

Answer 19

When nucleons bind together to form the nucleus some of the mass is converted into energy

Question 20

How can you find the nuclear binding energy?

Answer 20

Using mass defect equation