Nuclear Energy

People who contributed -

Madame Curie - atoms are made of smaller particles evidence in 1876-1934

discovered radioactivity - (specifically) the spontaneous disintegration of some elements into smaller pieces.

Antoine Henri Becquerel - Main person in the discovery of radioactivity in 1896

Vocabulary

Radioactivity - spontaneous emission of energy or particles by unstable atomic nuclei

Radiation - The emitted particles/energy

Radioactive decay - The change in the nucleus that results to make the isotopes outside of the band of stability, stable

Radioactive Isotopes/radioisotope - unstable isotopes that lie outside the band of stability

Nuclear Equations - equations that describe nuclear reactions

Nuclear Reactions - changes in the nucleus

Transmutation - reactions that result in the formation of a new element

Ex include: alpha, beta, gamma

Band of stability - (Why radioactive decay occurs)

This is a ratio of protons to neutrons that is inherently stable.

Atoms not in this band will undergo radioactive decay

Nucleons - protons and neutrons(mass of the nucleus)

Nuclide - atom/element (NOT nucleus)

Represented in 2 ways

Radium - 228 (mass #)

228 Ra (mass number A)

88 (atomic number Z)

Isotope - atoms of the same element that don’t have the same mass due

to different numbers of neutrons in those atoms.

Types of Radiation

3 types of radiation - alpha + , beta - , gamma 0 charge

Alpha has the least amount of energy while gamma has the most amount of energy

Alpha particles - reason for unstableness - too many protons (bigger than 82)

alpha emission results in the release of alpha particles

2 protons and 2 neutrons lost

Symbol a or 4(top) 2 (bottom) He(2+ charge)

Beta particles - 3 types of beta decay

Bminus(beta emission)/Bplus(positron emission)/InverseB(electron capture)

0 B minus(beta emission) electron emitted

Reason for unstableness - too many neutrons

Symbol B, B^- , 0(top) -1(bottom) e^-

Neutron becomes a proton and an electron(b particle that gets emitted)

0 B plus(positron emission) positron emitted

Reason for unstableness - too few neutrons

Symbol B^+ or 0(top) +1(bottom) e^+

Proton becomes a neutron and an anti-electron (positron)

(positron) - electron with a positive charge

0 Inverse B(electron capture/ e^- capture)

Instead of emitting an electron, it is pulled into the nucleus

Reason for unstableness - too few neutrons

Written inversed where symbol is 0(top)-1(bottom)e (same as beta emission)

Electron combines with proton to from neutron

(Product) Atomic number is lower by 1 with same mass like positron emission

Gamma rays - high energy photons

energy that is released as a result of radioactive decay

when in excited state, it goes to ground state, giving off photons in

the gamma region of the radiant energy spectrum

symbol is y or 0(top and bottom) y

no change to atomic number(charge) or mass

Frequently α or β decay produces energy,

which is released as gamma rays (γ).

In most cases, it is only given off when other

types of radiation occur, and since it has no

particles, its symbol is just γ.

Nuclear changes diagram - mass # A , atomic # Z

Mass and charge/atomic number need to be equal

in a balanced nuclear reaction

Half-Lives (t½)

0 The length of time it takes for a sample of a radioactive

element to decay to half its initial mass.

0 The amount of radioactive material present is a factor of how

many half-lives have passed since the initial mass was taken

0 Because the different radioactive nuclides have different stabilities, the rates at which

they decay differ as well.

0 Every radioisotope has a specific decay

0 Unique to each element

0 Half-life can range from billions of years to fractions of a second

0 Half-life can be a valuable tool when using radiation

0 Uranium-238 4.5 billion yrs , Polonium-214 165 microseconds (μs)