Chem Unit 2 - Decay, Fission, Fusion

Nuclear Force

Attractive force that keeps protons and neutrons together in the nucleus. Works at small distances

What does nuclear force dominate over?

Electromagnetic repulsion which forces particles of same charge away from each other

Strongest force on Earth

Nuclear force

Who coined the term radioactivity

Marie Curie

Unstable nuclei decay at a _____ rate

Unstable

How do unstable nuclei move toward the band of stability

Changing their nuclear structure

What does each dot on band of stability represent

stable nucleus

What can be concluded from the fact that as protons increase along x-axis, the neutron proton ratio increases?

Heavier elements need more neutrons to maintain stability

Do Isotopes exist beyond band of stability?

Yes, but they are unstable

What is the last dot on the band of stability?

Bismuth Z=83

Isotopes below 20 protons need a ____ ratio for stability

1:1

Isotopes between 60-80 protons need a ____ ratio for stability

1:5:1

Alpha decay

nucleus releases particle of 2 protons and 2 neutrons

What kind of nuclei do alpha decay?

Large nuclei

Which type of transmutation did Rutherford use in his experiment

Alpha decay with polonium

What is the particle taken out of nucleus in alpha decay?

₂⁴HE

Why must both sides of the equations for transmutation be equal in protons and neutron?

Law of conservation of mass

When does beta decay take place

When there are too many neutrons

What happens during beta decay

nucleus turns a neutron into a proton and an electron particle is ejected from the nucleus 

What happens to the mass number in beta decay

Stays the same 

What is the notation for beta decay?

_p+1^{Mass Same}Element + _-1⁰e

Which type of transmutation is very harmful to humans

Gamma decay

Gamma decay notation

y (greek letter)

When does positron decay take place

Too many protons

What happens during positron decay

Nucleus converts proton into neutron and positively-charged positron

What happens to mass number in positron decay?

Stays the same

What happens to atomic number in positron decay? Beta decay?

Positron decay - subtract 1

Beta decay - add 1

Positron decay equation

_p-1^{mass same}Element + ₊₁⁰e

When does electron capture take place

When there are too few neutrons

What happens during electron capture

An electron from the closest energy level falls into the nucleus which causes proton to become neutron

What happens to atomic number and mass number during electron capture

atomic number -1

mass number same 

Electron capture equation

x + _-1⁰e —> _p-1^{same mass}x

Fusion

Joins 2 or more lighter nuclei together to form heavier nuclei

Fission

Splitting of large nucleus by bombarding with neutron, creates smaller nuclei and certain number of neutrons

What is a self sustaining fission process called

A chain reaction