A nucleus can be specified By an atomic number and a Mass number.

7 Nitrogen N Atomic Number (Z) Name Symbol 14 Mass Number (A)

The typical Nitrogen atom has A mass number of 14. It has 7 protons and 7 neutrons. The atomic number never changes, However the mass can change. All atoms are electrically Neutral, thus the number Of protons equals the Number of electrons.

SymbolNameExplanation AMass NumberThe number of nucleons ZAtomic NumberThe number of protons NNeutron NumberThe number of neutrons

An isotope is when atoms of an Element having the same atomic Number but different Neutron and mass number. Hydrogen has 3 isotopes: Hydrogen Deuterium Tritium

Scientists measure Elements in AMU, or atomic Mass units. 1 AMU = 1/12 (mass of Carbon) = 1.66 X g So, one proton or one Neutron are about 1 AMU each.

The strong nuclear force is An attractive force that Overcomes the electrical Repulsion between protons. Nuclear reactions change The composition of An atoms nucleus!!

Binding energy is the energy Released when nucleons bind Together to form a Stable nucleus. E = mc 2

When a nucleus undergoes Nuclear decay, only three types Of radiation can be released… Alpha Beta Gamma

NAMEIDENTITYCHARGEPENETR- ATION ALPHA α He-4 NUCLEI 2+LOW BETA β ELECTR- ONS 1-MEDIUM GAMMA γ HIGH ENERGY X-RAY NONEVERY HIGH

Everybody thinks that this is so Hard, but there are only 2 rules… The total of the atomic numbers on The left is that same as the total On the right because charge Must be conserved. The total of the mass numbers on The left is the same as the total on The right because mass must Be conserved.

131 I  131 Xe + 0 β 5354 This is the nuclear equation That describes the beta Decay of iodine – 131. The numbers ALWAYS balance!

One of the isotopes of radium, 226 Ra, decays by alpha Emission. What is the resulting Daughter element? Ra  222 Rn + 4 α 88862

As things decay, it can Be measured. The SI unit of radioactivity is The becquerel, Bq. 1 Bq = 1 decay per second

The half-life is the time required To half the original nuclei Of a radioactive material to Undergo radioactive decay. T ½ = Decay constant

The 1/2 life of a radium nucleus is 5 X s. A sample contains 3 X nuclei. What is the decay Constant for this decay? How Many radium nuclei will decay Per second? Constant = 1.4 X Activity = Bq

There are 2 types of nuclear Reactions, fission & fusion.

Stable nuclei can be made Unstable by bombarding them With extra neutrons. Heavy nuclei can undergo Nuclear fission. Nuclear fission is the breaking Apart of a nucleus.

When nuclear fission occurs, Neutrons are released and can Trigger a chain reaction.

Light nuclei can undergo Nuclear fusion. Nuclear fusion is when two Nuclei are squished together. Stars work like this, up until Iron - 58, (the most stable element). Fusing elements after this require Energy, thus are made in A supernova.

All things in the universe are Created by very, very tiny Pieces of matter.

Many new particles have been Produced in accelerators. There are 4 fundamental Interactions in nature… Strong, Weak, Electromagnetic & Gravitational

A force can be thought of as Mediated by an exchange Of particles. Leptons are thought to be Elementary particles. Hadrons include mesons & baryons. Hadrons are thought to be made Of quarks.

There are 6 quarks… Up, Down, Charm, Strange, Top, Bottom. The standard model can help Explain the early universe.