14 Nuclear Decay

Question 1

A nucleus is held together by a nonelectrical, nongravitational force called

Answer 1

the nuclear force.

Question 2

Alph Emission (⁴₂ Alpha)

In alpha decay, the nucleus emits a particle that has the same constitution as a

Answer 2

helium molecule, with 2 protons and 2 neutrons. Alpha particles are the least penetrating of the products of nuclear decay.

⁴₂HE

Question 3

When a nucleus undergoes alpha decay

Answer 3

subtract 4 from the mass number

subtract 2 from the atomic number

Question 4

Beta Emission (0-₁Beta)

A beta particle is identical to an electron. In beta decay, the nucleus changes a neutron into a proton.

When a nucleus undergoes beta decay

Answer 4

the mass number remains the same

add 1 to the atomic number

Question 5

Positron Emission (^0₊₁Beta)

A positron is like an electron with a positive charge. In positron emission, the nucleus changes a proton into a neutron and a positrion and emits the positron.

When a nucleus undergoes positron emission

Answer 5

the mass number remains the same

subtract 1 from the atomic number

Question 6

Electron Capture (⁰_-1e)

In electron Capture, the nucleus captures a low energy electron and combine it with a proton to form a neutron.

When a nucleus undergoes electron capture

Answer 6

the mass number remains the same

subtract 1 from the atomic number

Question 7

Gamma Rays (⁰₀Y)

Gamma Rays are electromagnetic radiation, and have no mass and no charge. Gamma Rays usually accompany other forms of nuclear decay, and are the most penetrating of the nuclear decay products.

Question 8

If an isotope’s mass number is greater than its atomic weight (¹⁶₆ C, for instance)

Answer 8

the nucleus will try to gain protons and lose neutrons; therefore, if its mass number is greater than its atomic weight, you can expect beta decay.

Question 9

If an isotope’s mass number is less than its atomic weight (¹¹₆C, for instance),

Answer 9

the nucleus will try to lose protons and gain neutrons; therefore, if its mass number is less than its atomic weight, you can expect positron emission or electron capture.

Question 10

Alpha emission is seen mainly in very large nuclei,

Answer 10

usually with atomic number of 60 or greater

Question 11

E =

Answer 11

mc²

E = energy (J)

m = mass (Kg)

c = the speed of light, 3 X 10⁸ m/sec